ALE's `ale#other_source#ShowResults` API should understand the "H" (hint) type

## Information

**VIM version**

VIM - Vi IMproved 9.1 (2024 Jan 02, compiled Jan 01 1980 00:00:00)
Included patches: 1-1050

Operating System: NixOS

## What went wrong

ALE doesn't appear to accept "H" (hint) as a type for external LSP plugins communicating through `ale#other_source#ShowResults`. yegappan's vim9 script LSP plugin is attempting to send `H` (https://github.com/yegappan/lsp/blob/main/autoload/lsp/diag.vim#L359), but ALE defaults to `E` because it's only aware of only error, warning, and info.

ALE _should_ support hints through this API, but I am not very familiar with ALE's codebase so I'm not sure of the extent of changes required to add the additional type.

Images can be seen here: https://github.com/yegappan/lsp/issues/591

## Reproducing the bug

Enable `aleSupport` in yegappan's LSP. Hints are converted to errors.

Start at the ale#other_source#ShowResults API and compare its accepted diagnostic types with the H value sent from yegappan's lsp autoload/lsp/diag.vim at line 359. Trace where unsupported types default to E, then verify that H hints remain hints rather than becoming errors when ALE receives them.

Written by the indexing model from the issue text.