Implement QML deploying about go-appimage

[probonopd]

Qt itself is done, now for QML.

Need to be able to pass in one or multiple qml directories, e.g., using https://stackoverflow.com/questions/28322997/how-to-get-a-list-of-values-into-a-flag-in-golang/28323276

https://github.com/probonopd/linuxdeployqt/blob/42e51ea7c7a572a0aa1a21fc47d0f80032809d9d/tools/linuxdeployqt/shared.cpp#L1647

[probonopd]

qmlimportscanner -rootPath /home/me/untitled/ -importPath /tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/ gives

[
    {
        "classname": "QtQuick2Plugin",
        "name": "QtQuick",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick.2",
        "plugin": "qtquick2plugin",
        "relativePath": "QtQuick.2",
        "type": "module",
        "version": "2.7"
    },
    {
        "classname": "QtQuickControls2Plugin",
        "name": "QtQuick.Controls",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Controls.2",
        "plugin": "qtquickcontrols2plugin",
        "relativePath": "QtQuick/Controls.2",
        "type": "module",
        "version": "2.0"
    },
    {
        "classname": "QtQuickLayoutsPlugin",
        "name": "QtQuick.Layouts",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Layouts",
        "plugin": "qquicklayoutsplugin",
        "relativePath": "QtQuick/Layouts",
        "type": "module",
        "version": "1.0"
    },
    {
        "classname": "QtQuickTemplates2Plugin",
        "name": "QtQuick.Templates",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Templates.2",
        "plugin": "qtquicktemplates2plugin",
        "relativePath": "QtQuick/Templates.2",
        "type": "module",
        "version": "2.0"
    },
    {
        "classname": "QtQuick2WindowPlugin",
        "name": "QtQuick.Window",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Window.2",
        "plugin": "windowplugin",
        "relativePath": "QtQuick/Window.2",
        "type": "module",
        "version": "2.2"
    },
    {
        "classname": "QtQuick2Plugin",
        "name": "QtQuick",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick.2",
        "plugin": "qtquick2plugin",
        "relativePath": "QtQuick.2",
        "type": "module",
        "version": "2.8"
    },
    {
        "classname": "QtQuickTemplates2Plugin",
        "name": "QtQuick.Templates",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Templates.2",
        "plugin": "qtquicktemplates2plugin",
        "relativePath": "QtQuick/Templates.2",
        "type": "module",
        "version": "2.1"
    },
    {
        "classname": "QtQuickControls2MaterialStylePlugin",
        "name": "QtQuick.Controls.Material",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Controls.2/Material",
        "plugin": "qtquickcontrols2materialstyleplugin",
        "relativePath": "QtQuick/Controls.2/Material",
        "type": "module",
        "version": "2.1"
    },
    {
        "name": "QtQuick.Controls.Material.impl",
        "type": "module",
        "version": "2.1"
    },
    {
        "classname": "QtQuickControls2Plugin",
        "name": "QtQuick.Controls",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Controls.2",
        "plugin": "qtquickcontrols2plugin",
        "relativePath": "QtQuick/Controls.2",
        "type": "module",
        "version": "2.1"
    },
    {
        "classname": "QtQuick2Plugin",
        "name": "QtQuick",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick.2",
        "plugin": "qtquick2plugin",
        "relativePath": "QtQuick.2",
        "type": "module",
        "version": "2.0"
    },
    {
        "name": "QtQuick.Controls.impl",
        "type": "module",
        "version": "2.1"
    },
    {
        "classname": "QtQuickControls2UniversalStylePlugin",
        "name": "QtQuick.Controls.Universal",
        "path": "/tmp/.mount_QtCreator-5.8.0-x86_64/5.8/gcc_64/qml/QtQuick/Controls.2/Universal",
        "plugin": "qtquickcontrols2universalstyleplugin",
        "relativePath": "QtQuick/Controls.2/Universal",
        "type": "module",
        "version": "2.1"
    },
    {
        "name": "QtQuick.Controls.Universal.impl",
        "type": "module",
        "version": "2.1"
    }
]

which we could probably model as a Go struct like this:

type QMLImport []struct {
	Classname    string `json:"classname,omitempty"`
	Name         string `json:"name"`
	Path         string `json:"path,omitempty"`
	Plugin       string `json:"plugin,omitempty"`
	RelativePath string `json:"relativePath,omitempty"`
	Type         string `json:"type"`
	Version      string `json:"version"`
}

[probonopd]

• Skip imports with missing name or path (path will be empty if the import is not found)
• Deploy module imports only, skip directory (local/remote) and js imports. These should be deployed as a part of the application build
• Special case: Use of QtQuick/PrivateWidgets is not discoverable at deploy-time. Deploy it if QtWidgets library is used and QtQuick.Controls is used

[probonopd]

Implemented