Priority for function definitions in external files over local script

[Qwark-878]

Description:
When a function is defined both in an external file (e.g., qlua.d.lua) and in the local script, Lua Language Server prioritizes the local definition. This behavior makes it difficult to use external annotations and documentation for functions that are implemented locally.

Steps to reproduce:
Define a function in qlua.d.lua with annotations:
lua
Copy
---@param index number
---@return number|nil
function OnCalculate(index) end
Define the same function in the local script without annotations:

lua
Copy
function OnCalculate(index)
-- Implementation
end
Hover over the function in the local script.

Expected behavior:
Lua Language Server should prioritize the definition from qlua.d.lua for tooltips and documentation.
Actual behavior:
Lua Language Server uses the local definition, ignoring the one from qlua.d.lua.
Proposed solution:
Add an option to prioritize definitions from external files over local ones. For example, a setting like:

json
Copy
{
"Lua.workspace.prioritizeExternalDefinitions": true
}
VS Code
Ver: 1.98.0 (user setup)
Фиксация: 6609ac3d66f4eade5cf376d1cb76f13985724bcb
Data: 2025-03-04T21:06:18.612Z
Electron: 34.2.0
ElectronBuildId: 11044223
Chromium: 132.0.6834.196
Node.js: 20.18.2
V8: 13.2.152.36-electron.0
OS: Windows_NT x64 10.0.19045
LUA:
ID- sumneko.lua
Ver- 3.13.6