Add flag to include all files in scan about wordfence-cli

[akenion]

Additionally, the help messaging should be updated to indicate that only files matching certain patterns are scanned by default.

[akenion]

The above PR also implements a shorthand -a flag as an alias for --include-all-files.

[ewodrich]

Verified the changes are working as expected including the following:

1. new command –-include-all-files and -a displays in —help as expected, and that the help mentions "By default, only files matching certain extensions are scanned"
2. Scanning with --include-all-files works as expected, without error. Also compared the number of files scanned using this option vs the total number of files skipped + total number of files scanned with default settings equal the same totals.
3. Scanning with -a works as expected, without error. Also compared the number of files scanned using this option vs the total number of files skipped + total number of files scanned with default settings equal the same totals.
4. Additional testing completed with new options that includes

• with Free key
• with Premium key
• scanning recursive symlinks work as before (see note below)
• -a and --include-all-files produce the same number of files
• --include-files-pattern=.* produces same result as -a
• --include-files continues to work as intended
• --exclude-files continues to work as intended
• using -a in combination with --exclude-files-pattern or --exclude-files works as anticipated by scanning all files except those defined to be excluded
• results route to --output-path

While testing this case, opened Case #74 for a new finding when scanning a directory with a symlink pointing above the target directory either producing an error or placing the scan into a loop.