Remove dependency on tsconfig.paths.json

[Adjective-Object]

tsconfig.paths.json is nonstandard, and only used to get an accounting of:

• what package names map to what package paths
• how output paths map to source paths

Both of these are available elsewhere!

• package_name -> package paths: we can discover this by looking at package.json files during the source walk
• package/lib/foo -> packages/src/foo.ts mapping: we can look this up by resolving the "source' export condition from those package.Json files