…manager (#54819)

`ImportGenerator` is the abstraction used by the translator functions to
insert imports for `ExternalExpr` in an AST-agnostic way.

This was built specifically for the linker which does not use any of the
complex import managers- but rather re-uses `ngImport` or uses
`ngImport.Bla`.

This commit also switches the linker AST-agnostic generator to follow
the new signatures. This was rather trivial.

PR Close #54819

…54819)

This commit switches ngtsc's JS and DTS transform to use the new import
manager. This is a drop-in replacement as we've updated the translator
helpers in the previous commit to align with the new API suggested by
the `ImportManagerV2` (to be renamed then).

PR Close #54819

…import manager (#54819)

Updates the type-check block generation code (also for inline type check
blocks) to use the new import manager.

This is now a requirement because the translator utilities from the
reference emit environment expect an import manager that follows the
new contract established via `ImportGenerator<TFile, TExpression>`.

For type check files, we can simply print new imports as we don't expect
existing imports to be updated. That is because type check files do not
have any _original_ source files (or in practice— those are empty).

For type check blocks inline, or constructors, imports _may_ be re-used.
This is great as it helps fixing some incrementality bugs that we were
seeing in the type check code. That is, sometimes the type check block
code may generate imports conditionally for e.g. `TemplateRef`, or
animations. Those then **prevent** incremental re-use if TCB code
switches between those continously. We tried to account for that with
signal inputs by always pre-generating such imports. This fixed the
issue for type-check files, but for inline type check blocks this is
different as we would introduce new imports in user code that would then
be changed back in subsequential edit iterations. See:
#53521 (review).

In practice, the assumption was that we would be fine since user code is
most likely containing imports to `@angular/core` already. That is a
true assumption, but unfortunately it doesn't help with incremental
re-use because TypeScript's structural change detection does not dedupe
and expects 1:1 exact imports from their old source files.

microsoft/TypeScript#56845

To improve incremental re-use for the type check integration, we should
re-use original source file imports when possible. This commit enables
this.

To update imports and execute inline operations, we are now uisng
`magic-string` (which is then bundled) as it simplifies the string
manipulatuons.

PR Close #54819

…er (#54819)

Switches the JIT transforms to use the new import manager.

PR Close #54819

…al inputs (#54819)

Enables the incremental type-checking test that we never enabled when we
landed signal inputs. Now that we fixed incremental re-use by re-using
the existing user imports for inline type check blocks, the test is
passing and can be enabled.

PR Close #54819

This commit deletes the older and now unused `ImportManager`.

PR Close #54819

…54819)

To ease review and to allow for both instances to co-exist, `ImportManagerV2`
was introduced. This commit renames it to `ImportManager` now that we
deleted the older one.

PR Close #54819

…s/blocks (#54819)

This commit adds some unit tests verifying the import generation in TCB
files and inline blocks. We don't seem to have any unit tests for these
in general. This commit adds some, verifying some characteristics we
would like to guarantee.

PR Close #54819

)

This commit updates the logic for preserving file overview comments
to be more reliable and less dependent on previous transforms.

Previously, with the old import manager, we had a utility called
`addImport` that always separated import statements and non-import
statements. This meant that the non-emitted statement from Tsickle
for the synthetic file-overview comments no longer lived at the
beginning of the file.

`addImports` tried to overcome this by adding another new non-emitted
statement *before* all imports. This then was later used by the
transform (or was assumed!) to attach the synthetic file overview
comments if the original tsickle AST Node is no longer at the top.

This logic can be improved, because the import manager shouldn't need to
bother about this fileoverview non-emitted statement, and the logic for
re-attaching the fileoverview comment should be local. This commit fixes
this and makes it a local transform.

PR Close #54819