Add the ability to introduce repository specific configurations for gh-cli and its extensions about go-gh

[samcoe]

@tjgurwara99 Thanks for the feature request. This type of feature has come up a couple times in the cli/cli repo, mainly around being able to support multiple accounts GitHub accounts and switching them based on the current local repository. I think gh itself should be vary wary of creating its own per repository config files as that greatly complicates the reading and writing of gh configurations, but if an extension wants to create its own configuration files I think we can support that.

Right now the limiting factor for this feature is the hardcoded locations for reading and writing configuration files using the generalConfigFile() and hostsConfigFile() functions as you mentioned. I think if we introduced two new functions to the config package ReadFromPath(path string) (*Config, error) and WriteToPath(path string, c *Config) error that would allow extensions to read/write/manipulate yaml files and it would be on the extensions to manage their own configuration files as they see fit.

Note that the config package only has infrastructure for working with yaml files so I don't think we will want to support any other formats.

What do you think of this approach?

[tjgurwara99]

I think if we introduced two new functions to the config package ReadFromPath(path string) (*Config, error) and WriteToPath(path string, c *Config) error that would allow extensions to read/write/manipulate yaml files and it would be on the extensions to manage their own configuration files as they see fit.

This sounds good to me. I think its a good approach as this would provide the extension owner the freedom to set their configuration however they see fit.