fix(language-service): resolve symbols for inputs with restricted access - #71139

When strictInputAccessModifiers is disabled (the default, even with strictTemplates), bindings to input fields with restricted access (private/protected/readonly) are type-checked through a temporary variable rather than by assigning to the field directly. The type of this variable was generated as an indexed access type (typeof _t1)["fieldName"], which TypeScript does not treat as a reference to the class member. As a result, quick info, go to definition, find references and rename did not work for such inputs, e.g. for readonly signal inputs.

The type of the temporary variable is now generated as a type query with a qualified name, typeof _t1.fieldName, which TypeScript resolves as a regular reference to the class member. Reading a private/protected field through the type query is an access violation, so diagnostics are ignored for the type node, while the assignment into the temporary variable remains fully type-checked. The symbol builder now resolves the input symbol through the temporary variable's declaration instead of bailing out.

Fixes #58284

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/contributing-docs/commit-message-guidelines.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.dev application / infrastructure changes
• Other... Please describe:

What is the current behavior?

When strictInputAccessModifiers is disabled (the default, even with strictTemplates),
bindings to input fields with restricted access (private/protected/readonly) are type-checked through a temporary variable typed with an indexed access type ((typeof _t1)["fieldName"]). TypeScript does not treat the string literal in an indexed access type as a reference to the class member, and the symbol builder bails out when the
binding target is a temporary variable. As a result, quick info, go to definition, find references and rename do not work for such inputs — e.g. readonly signal inputs.

Issue Number: #58284

What is the new behavior?

The temporary variable is now typed with a type query using a qualified name
(typeof _t1.fieldName), which TypeScript resolves as a regular reference to the class member, so references/rename work in both directions (template → class and class → template).
Reading a private/protected field through the type query would be an access violation, so diagnostics are ignored for the type node, while the assignment into the temporary variable remains fully type-checked. The symbol builder now resolves the input symbol through the temporary variable's declaration instead of bailing out.

Does this PR introduce a breaking change?

• Yes
• No