Add build instructions for developers

[smatting]

This PR

• adds documentation for how to build wire-server to ./docs/developer/building.md (and link from README.md in project root)
• includes hie.yaml in repo (so it doesn't have to be generated)
• add makefile target for cabal.project.local file
• update delete-cache-on-linker-errors makefile target: delete ~/.cabal/store instead of ~/.cabal

Checklist

• The PR Title explains the impact of the change.
• The PR description provides context as to why the change should occur and what the code contributes to that effect. This could also be a link to a JIRA ticket or a Github issue, if there is one.
• If this PR changes development workflow or dependencies, they have been A) automated and B) documented under docs/developer/. All efforts have been taken to minimize development setup breakage or slowdown for co-workers.
• changelog.d contains the following bits of information (details):
  • A file with the changelog entry in one or more suitable sub-sections. The sub-sections are marked by directories inside changelog.d.

[smatting]

I'd like to remove these variables in a separate PR

[jschaul]

Thanks! Looks good! Note that this may conflict with #2623 in that one makefile target so a rebase might be needed if that other PR is merged first.

[fisx]

This also conflicts with #2622, but it should be easy to fix: just rebase whoever goes second over the other, git mv docs/developer/building.md docs/src/developer/developer/building.md, and add a toc entry to docs/src/developer/index.rst.

[smatting]

Thanks! Looks good! Note that this may conflict with #2623 in that one makefile target so a rebase might be needed if that other PR is merged first.

I removed the duplicated changes from this PR.