refactor(compiler-cli): remove i18n options from LinkerOptions

[petebacondarwin]

There were three options being made available to users of the linker:

• enableI18nLegacyMessageIdFormat
• i18nNormalizeLineEndingsInICUs
• i18nUseExternalIds

None of these should actually be configurable at linking time
because partially-linked libraries have tighter restrictions on
what i18n options can be used.

This commit removes those options from the LinkerOptions interface.
It was considered to add a check for backwards compatibilty to ensure
that if these options were being passed, and were different to the expected
defaults, we would throw an informative error. But from looking at the
Angular CLI (the only known client of the linker) it has never been setting
these options so they have already always been set to the defaults.

BREAKING CHANGE:

Linked libraries no longer generate legacy i18n message ids. Any downstream
application that provides translations for these messages, will need to
migrate their message ids using the localize-migrate command line tool.

Closes #40673

[JoostK]

LGTM. I am not sure about the deprecation notice, given that partial compilation/the linker has not been stable so in and of itself I wouldn't consider this change as breaking. It is however true that a library that switches to partial compilation would indeed be breaking, as the application's compilation options are no longer considered (so no more legacy message ids nor is preserveWhitespaces taken into account anymore). I notice you put this on the meeting agenda so let's discuss there. In any case, I think the deprecation notice can not go into a refactor commit as those are excluded from the changelog.

[devversion]

LGTM for dev infra

[zarend]

hi @petebacondarwin, I am unable to merge this because it has a merge conflict with the master branch 😢 .

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