Show provenance of import constraint

With this change to the solver message rendering, I also fix some bugs around project imports, adding tests for those cases. Reviewers asked that the Y-shaped import checks (using IORef) be made on a separate pull request. Removing those lead to cascading deletions.

- Regenerate expected .out files
- Show tree provenance of import constraint
- Add trimmed down PackageTests/VersionPriority
- Add changelog entry
- Use NonEmpty
- Fix check for cyclical import
- Use primes for next iteration
- Remove unused LANGUAGE pragmas
- Rename to projectConfigPathRoot
- Docs for ProjectConfigPath and showProjectConfigPath
- Renaming
- Add cyclical import tests with 1 and 2 hops in cycle
- Use full path for cyclical error message
- Expected output has project with full project path
- Add fullPath local function
- Project directory as FilePath, not Maybe FilePath
- Use (_, projectFileName) binding splitFileName
- Need full path to project parsing legacy
- Inline seenImports conversion
- Add cyclical checks with same file names and hops
- Add noncyclical tests that hop over folders
- Add a project testing skipping in and out of a folder
- Update expectations of cyclical tests
- Use canonicalizePath for collapsing .. when possible
- Capture trace for later
- Add module for ProjectConfigPath
- Move functions for ProjectConfigPath to its module
- Fetch URI is not prefixed with ./https://etc
- Document normaliseConfigPath
- Add doctests for normaliseConfigPath
- Add doctest of canonicalizeConfigPath
- Show an example of canonical paths
- Use importer and importee in canonicalizeConfigPaths
- Add logging