Advance multiroot workspace support

[tolezk]

So, this commit introduces some changes. The most noticeable change is multiroot workspace support in a quite flexible way.

[tolezk]

Hi @idanpa,

Basing on our short conversation here I propose everythig I asked in #7.

[idanpa]

@tolezk I might need a few extra days to go over this change and to test it. Are these changes only addressing #7? fixing only these two things

1. allow user to add --showfile in args
2. have multiple different .checkpatch.conf files across the files

? (seems too much code to me, but need to take a deeper look)

[tolezk]

Probably it may look like a mess (sorry for that, but I decided it's better to go as is than not to go) but this change does the following:

• fixes --showfile issue
• fixes --show-types issue (related to check commit command)
• adds support for folder-specific .checkpatch.conf (multiroot)
• adds support for folder-specific .checkpatch.pl (multiroot)
• adds separate checkpathch section in output pane to have logs from extension (handy sometimes)
• adds Clear Current Diagnostic command (useful sometimes)
• slightly rearranges commands naming (to make a search in the command palette easier)
• slightly rearranges messages that are shown in popups (to easier get what caused the popup)

[tolezk]

@idanpa please provide any feedback and I'll try to find some bandwidth to rearrange this in a way to make it easier to validate all the changes for you. Or let me know if you gonna reject this.