✨ Filetype associations and icons

[austincondiff]

Describe the solution you'd like

Files that can be opened with CodeEdit should get filetype associations so that they can be opened from Finder. They should also get filetype icons.

Additional context

Originally discussed in #613 by @AsedaDeveloper and brought up by @Acc3ssD3n13d in #613 (comment).

[0xWDG]

Do we want something like Xcode (project/workspace file/directory)?
Should it contain custom editor settings?

[austincondiff]

@wdg This issue isn't about the workspace file itself (That will be in .codeedit/preferences.json or something similar). It is moreso around when you open a file from Finder, we want relevant files to open in CodeEdit.