[Feature Request] Add Lua config file support

[goldenstein64]

There are some Lua files that are used for configuration, such as .busted or *.rockspec files. It would be nice if:

• Any globals defined in them are ignored by default
• Global types and return types can be defined for them in a type definition file

This behavior could all be described by creating a type definition file with a special (config) option next to @meta. The require name is replaced by a Lua pattern that matches the filename or URI. Either that, or it could be specified as a config-specific option using ---@meta (config: PATTERN)

-- library/rockspec.d.lua

---@meta (config) "[%w%.%-%_]+%.rockspec$"

---the rockspec format
---@type string
_G.rockspec_format = nil

---the package name
---@type string
_G.package = nil

---the package version
---@type string
_G.version = nil

---a description of the rock
---@class luarocks.rockspec.description
---@field summary string? -- a short sentence that succinctly describes the rock
---@field description string? -- a paragraph-size description that describes the rock
---@field ...
_G.description = {}

For configurations that require returning a table, you could define a local variable with the right type and return it.

-- library/busted.d.lua

---@meta (config) "%.busted$"

---@class .busted.config
---@field coverage boolean? -- use luacov for coverage
---@field verbose boolean? -- print more things
---@field ...

---a dictionary of Busted configurations. You can specify which one using the
---`--run` option. Uses `default` if no configuration is specified
---@class .busted
---@field default .busted.config?
---@field [string] .busted.config?
local busted_config = {}

return busted_config