Solid: Some fixes for library and component generation. Fix for playground initialisation.

[ricrachac]

#1161
Removes an extra libs in the path when updating tsconfig.base.json. The path to the project can be handled by the options.projectDirectory as is.

nx g @nxext/solid:lib hello --directory packages/hello
nx g @nxext/solid:lib libs/world
cat tsconfig.base.json
...
"paths": {
      "@proj/hello": ["packages/hello/src/index.ts"],
      "@proj/world": ["libs/world/src/index.ts"]
    }
...

#1162
TS extension in component export causes issues as we don't have allowImportingTsExtensions. Removing it works as expected.

---

Misc
Playground error when trying to set up development enviroment. There is no longer a preset empty it seems. nx20 broke a few things in that regard when moving to the new workspace model I think.

NX   Unable to resolve empty:preset.
The "empty" package does not support Nx generators.