feat(compiler): support a non-null postfix assert (#16672)

Template expressions can now use a post-fix `!` operator
that asserts the target of the operator is not null. This is
similar to the TypeScript non-null assert operator. Expressions
generated in factories will be generated with the non-null assert
operator.

Closes: #10855

packages/language-service/src/expressions.ts

@@ -69,6 +69,7 @@ export function getExpressionCompletions(
       }
     },
     visitPrefixNot(ast) {},
+    visitNonNullAssert(ast) {},
     visitPropertyRead(ast) {
       const receiverType = getType(ast.receiver);
       result = receiverType ? receiverType.members() : scope;
@@ -138,6 +139,7 @@ export function getExpressionSymbol(
       }
     },
     visitPrefixNot(ast) {},
+    visitNonNullAssert(ast) {},
     visitPropertyRead(ast) {
       const receiverType = getType(ast.receiver);
       symbol = receiverType && receiverType.members().get(ast.name);