Refactors the `ng_rollup_bundle` rule to a macro that relies on
the `@bazel/rollup` package. This means that the rule no longer
deals with custom ESM5 flavour output, but rather only builds
prodmode ES2015 output. This matches the common build output
in Angular projects, and optimizations done in CLI where
ES2015 is the default optimization input.
The motiviation for this change is:
* Not duplicating rollup Bazel rules. Instead leveraging the official
rollup rule.
* Not dealing with a third TS output flavor in Bazel.The ESM5 flavour has the
potential of slowing down local development (as it requires compilation replaying)
* Updating the rule to be aligned with current CLI optimizations.
This also _fixes_ a bug that surfaced in the old rollup bundle rule.
Code that is unused, is not removed properly. The new rule fixes this by
setting the `toplevel` flag. This instructs terser to remove unused
definitions at top-level. This matches the optimization applied in CLI
projects. Notably the CLI doesn't need this flag, as code is always
wrapped by Webpack. Hence, the unused code eliding runs by default.
PR Close#37623