Problem:
`:checkhealth vim.lsp` validates configured filetypes against
`getcompletion('', 'filetype')`. This only reflects runtime support
files.
This causes false warnings in `:checkhealth vim.lsp` for configured
filetypes that are known to the Lua filetype registry, including
values added with `vim.filetype.add()` and built-in registry-only
filetypes.
Solution:
Build the healthcheck's known-filetype set from both
`getcompletion('', 'filetype')` and `vim.filetype.inspect()`.
20a3254ad4