Better global

I'm going to do some work for global variable distinguishing environments.
At present, my idea is as follows:

---@global global -- the table will be merged into current globals. the second `global` can be omitted
local t = {
    X = 1,
    Y = 2,
    Z = 3,
}

print(X) -- `X` is `t.X`

---@global module1, module2 -- the table will be merged into environment `module1` and `module2`
local t = {
    X = 1,
    Y = 2,
    Z = 3,
}

print(X) -- `x` is undefined

---@environment module1, global -- set the current environment can visit `module1` and `global`
print(X) -- `X` is `t.X`

---@environment module1
print(X) -- `X` is `t.X` and `print` is undefined

EDIT:

---@partial class _G -- the table will be merged into class `_G`. the default environment is class `_G`
local t = {
    X = 1,
    Y = 2,
    Z = 3,
}

print(X) -- `X` is `t.X`

---@class module1
local t = {
    X = 1,
    Y = 2,
    Z = 3,
}

print(X) -- `x` is undefined

---@environment module1, _G -- set the current environment can visit class `module1` and `_G`
print(X) -- `X` is `t.X`

---@environment module1
print(X) -- `X` is `t.X` and `print` is undefined

该 issue 提出了新的 @global、@partial、@class 和 @environment 注解，用于区分 Lua 环境，但没有指定文件、测试或入口点。首先明确预期的环境和合并语义，然后定位注解和全局解析的实现。完成的标准是：提议的示例能够按描述解析全局变量，并且涵盖不同的环境组合。