[clang-tools-extra] [clangd] Store documentation when indexing standard library (PR #133681)

[kadir çetinkaya via cfe-commits]

kadircet wrote:

> The described options seem a bit more involved than necessary to fix this bug, given that it's just the value of the `StoreAllDocumentation` flag that's a problem.

Maybe I miscommunicated something, but I was talking about a change like https://github.com/kadircet/llvm-project/commit/ff0c31d232b2aed9e95d69d16a9dfbb9babea711.

> I revised the patch to add a new parameter to `createStaticIndexingAction()` (now called `createIndexingAction()`) and set the flag based on that -- does this address your concern about callers having to decide whether they want `StoreAllDocumentation`?

I think this still leaves possibility for future divergences. Conceptually we should either make stdlib index act as dynamic-index (what I am suggesting) or change its priority to be similar to static-index. Otherwise we're likely to hit more discrepancies as the code evolves. Moreover changing `createStaticIndexingAction` also increases the mental load around all the complicated indexing architecture now.

https://github.com/llvm/llvm-project/pull/133681