fix(language-service): properly evaluate types in comparable expressions (#36529)

This commit fixes how the language service evaluates the compatibility
of types to work with arbitrary union types. As a result, compatibility
checks are now more strict and can catch similarities or differences
more clearly.

```
number|string == string|null  // OK
number|string == number       // OK
number|string == null         // not comparable
number == string              // not comparable
```

Using Ivy as a backend should provide these diagnoses for free, but we
can backfill them for now.

Closes https://github.com/angular/vscode-ng-language-service/issues/723

PR Close #36529

packages/language-service/src/symbols.ts

@@ -192,42 +192,47 @@ export enum BuiltinType {
   /**
    * The type is a type that can hold any other type.
    */
-  Any,
+  Any = -1,  // equivalent to b11..11 = String | Union | ...
+
+  /** Unknown types are functionally identical to any. */
+  Unknown = -1,
 
   /**
    * The type of a string literal.
    */
-  String,
+  String = 1 << 0,
 
   /**
    * The type of a numeric literal.
    */
-  Number,
+  Number = 1 << 1,
 
   /**
    * The type of the `true` and `false` literals.
    */
-  Boolean,
+  Boolean = 1 << 2,
 
   /**
    * The type of the `undefined` literal.
    */
-  Undefined,
+  Undefined = 1 << 3,
 
   /**
    * the type of the `null` literal.
    */
-  Null,
+  Null = 1 << 4,
 
   /**
    * the type is an unbound type parameter.
    */
-  Unbound,
+  Unbound = 1 << 5,
 
   /**
    * Not a built-in type.
    */
-  Other
+  Other = 1 << 6,
+
+  Object = 1 << 7,
 }
 
 /**