bug#63867: 29.0.91; typescript-ts-mode does not highlight function signature overloads

[Eli Zaretskii]

> From: Jimmy Yuen Ho Wong <wyuenho@gmail.com>
> Date: Sat, 03 Jun 2023 10:37:07 +0100
> 
> 
> Reproduction:
> 
> 1. C-x C-f test.ts
> 2. Insert:
> 
> ```typescript
> function fn():void;
> function fn(arg1?:number, arg2?:string):void {
> }
> ```
> 
> 3. Observe the fn in the overload signature isn't highlighted as a
> function name
> 
> Expectation:
> 
> Function signature overloads should highlight the function names.

Thanks.

Guys, could you please look into fixing this?