[Feature Request] Option to have docs on numeric keys on tables

For example, a map of status code to some table.

local my_status_code_map = {
  -- attached docs
  -- attached docs (continued)
  [200] = { something = "here" }
}
local foo = my_status_code_map[200]
--                            ^^^^^--- i'd like to be able to hover here to get the docs attached to `[200]` in the table

该 issue 没有列出文件、测试或入口点；首先定位 Lua language server 中的悬停处理和表键解析。完成的标准是：将鼠标悬停在 my_status_code_map[200] 上时显示附加到 [200] 的文档，并为数值键示例提供覆盖。