build: eslint integration

[LeoDog896]

This adds the eslint toolchain to the repository, based on the config used in desktop/desktop.

I wanted to avoid breaking changes in this PR, but there are a few notable problems:

• eslint noticed an odd static class wrapper in git-process.ts that can easily be replaced with a collection of exported static methods
• The no-namespace rule had to be disabled to satisfy the Jest extension config - there is a notable comment under this StackOverflow post about this issue (I may look into this later)
• Since I've taken the config directly from desktop/desktop (while dropping react), there are probably a few rules that can be removed.