The Angular Core and localize package currently use deep imports for
code that is shipped. This is problematic as we want to ship the
compiler-cli as full-ESM. To achieve this we need to use a bundler and
this breaks deep imports.
We use a bundler for the compiler CLI because for full ESM
compatibility, we would need to explicitly add the `.js` extension
to all relative imports. This is very cumbersome and prone to mistakes
so to mitigate this problem in a safe way, we bundle the compiler-cli.
Note: Deep imports continue to exist for the language service as it
bundles the compiler-cli.
PR Close#43431
