[clangd] Improve inlay hints of things expanded from macros

When we aim a hint at some expanded tokens, we're only willing to attach it
to spelled tokens that exactly corresponde.

e.g.
int zoom(int x, int y, int z);
int dummy = zoom(NUMBERS);

Here we want to place a hint "x:" on the expanded "1", but we shouldn't
be willing to place it on NUMBERS, because it doesn't *exactly*
correspond (it has more tokens).

Fortunately we don't even have to implement this algorithm from scratch,
TokenBuffer has it.

Fixes https://github.com/clangd/clangd/issues/1289
Fixes https://github.com/clangd/clangd/issues/1118
Fixes https://github.com/clangd/clangd/issues/1018

Differential Revision: https://reviews.llvm.org/D133982