refactor(ivy): correctly type class declarations in ngtsc/ngcc (#29209)

Previously, several `ngtsc` and `ngcc` APIs dealing with class
declaration nodes used inconsistent types. For example, some methods of
the `DecoratorHandler` interface expected a `ts.Declaration` argument,
but actual `DecoratorHandler` implementations specified a stricter
`ts.ClassDeclaration` type.

As a result, the stricter methods would operate under the incorrect
assumption that their arguments were of type `ts.ClassDeclaration`,
while the actual arguments might be of different types (e.g. `ngcc`
would call them with `ts.FunctionDeclaration` or
`ts.VariableDeclaration` arguments, when compiling ES5 code).

Additionally, since we need those class declarations to be referenced in
other parts of the program, `ngtsc`/`ngcc` had to either repeatedly
check for `ts.isIdentifier(node.name)` or assume there was a `name`
identifier and use `node.name!`. While this assumption happens to be
true in the current implementation, working around type-checking is
error-prone (e.g. the assumption might stop being true in the future).

This commit fixes this by introducing a new type to be used for such
class declarations (`ts.Declaration & {name: ts.Identifier}`) and using
it consistently throughput the code.

PR Close #29209

packages/compiler-cli/src/ngtsc/annotations/test/directive_spec.ts

@@ -13,6 +13,7 @@ import {PartialEvaluator} from '../../partial_evaluator';
 import {TypeScriptReflectionHost} from '../../reflection';
 import {LocalModuleScopeRegistry, MetadataDtsModuleScopeResolver} from '../../scope';
 import {getDeclaration, makeProgram} from '../../testing/in_memory_typescript';
+import {isNamedClassDeclaration} from '../../util/src/typescript';
 import {DirectiveDecoratorHandler} from '../src/directive';
 
 
@@ -47,7 +48,7 @@ describe('DirectiveDecoratorHandler', () => {
         reflectionHost, evaluator, scopeRegistry, NOOP_DEFAULT_IMPORT_RECORDER, false);
 
     const analyzeDirective = (dirName: string) => {
-      const DirNode = getDeclaration(program, 'entry.ts', dirName, ts.isClassDeclaration);
+      const DirNode = getDeclaration(program, 'entry.ts', dirName, isNamedClassDeclaration);
 
       const detected = handler.detect(DirNode, reflectionHost.getDecoratorsOfDeclaration(DirNode));
       if (detected === undefined) {