[clang] [llvm] [LLVM][Clang] Add and enable strict mode for `getTrailingObjects` (PR #144930)

[Rahul Joshi via cfe-commits]

jurahul wrote:

Sure: The first line of the description attempts to define it:

> Under strict mode, the templated getTrailingObjects can be called only when there is > 1 trailing types.

I essentially used this strict mode to find all templated calls to `getTrailingObjects<X>` that could be converted to the simplified non-templated form `getTrailingObjects` in the series of PRs I did over last month. Essentially, what this will do is that any future user of TrailingObjects with a single trailing type will be forced to use the non-templated `getTrailingObjects`.

https://github.com/llvm/llvm-project/pull/144930