chore(Coder plugin): import preview version of Coder SDK into plugin

[Parkreiner]

Scaffolding needed for #114

Changes made

• Brought in vendored versions of the Coder core files

Notes

• For the most part, it can be assumed that all vendored files come directly from Coder core's api section
  • Had to make a few changes to satisfy Backstage's ESLint rules, but I'm going to try highlighting the important parts. Otherwise, you can ignore api.ts and typesGenerated.ts
  • In practice, this PR is like 70 lines long
  • Though I do think there are a few things that the linter caught that are worth updating in core. Will try to make a PR soon

[Parkreiner]

@code-asher Turning this back into a draft really quickly, because I'm realizing that I want to try hiding some of the methods from the core Coder stuff that wouldn't ever be relevant to a Backstage user (things like JFrog)