[Feature-Request/Question] Hide diagnostics while keeping require definitions for project files

Nobody has claimed this yet.

I have a project, where I use luarocks with modules directly installed in the projects folder (similar to how npm does it), which is handy for adding require paths, however what should I do, if they raise warnings?

I tried the following:
```json
{
"Lua.runtime.version": "LuaJIT",
"Lua.workspace.library": [
"${3rd}/love2d/library",
"${3rd}/lfs/library",
"${workspaceFolder}/lua_modules"
],
"Lua.runtime.path": [
"src/?.lua",
"src/?/init.lua",
"doc/?.lua",
"${workspaceFolder}/share/lua/5.1/?.lua",
"${workspaceFolder}/share/lua/5.1/?/init.lua"
],
"Lua.workspace.ignoreDir": [
"extern",
"lua_modules" // Need option to ignore diagnostics, but keep definitions
],
"Lua.diagnostics.libraryFiles": "Disable",
}
```

Start by inspecting how Lua.workspace.ignoreDir and Lua.diagnostics.libraryFiles are handled, using the configuration shown in the issue as the entry point. Trace how lua_modules is excluded from diagnostics and how its definitions are still discovered for require paths. Done means project-local modules remain available for definitions while their warnings are suppressed; no files or tests are named in the issue.

Written by the indexing model from the issue text.