fix: improve type narrow with literal alias param during completion and signature help

[tomlau10]

This supports type narrow during completion and signature help when function params are using @alias with literal values, as requested here: #1456 (comment)

Example use case:

---@alias events.AAA
---| "AAA" # description to AAA
---@alias events.BBB
---| "BBB" # description to BBB

---@class Emitter
---@field on fun(self: self, event: events.AAA,  cb: fun(a: integer))
---@field on fun(self: self, event: events.BBB, cb: fun(b: string))
local Emitter = {}

Emitter:on('BBB', <??>) --< trigger completion will suggest `fun(b: string)`, instead of showing both

中文版

上述 issue comment 作者想用 @alias 來定義 event name，因為這樣可以對 enum value 加 description，但發現用 alias 後做 completion 時無法做 type narrow。
這個 PR 是想在做 completion 和 signature help 時，增加檢查 function param 對應的 literal values 是否符合 event name

• 如果 function param 沒有 literal value => 無從判斷，維持原狀不會 narrow
• 有 literal values，並且至少 1個跟 call param literal value 是 match => 允許
• 有 literal values，但無一跟 call param literal value 是 match => 過濾掉