Overload type narrowing based on number of arguments instead of argument-type

還沒有人認領這個 Issue。

With the following code:
```
---@overload fun(param1: "test", param2: string)
---@overload fun(param1: "test2", param2: number)
---@overload fun(param1: "test3", param2: boolean, param3: number)
local function test(...)
end

test("test", "string"); ---expected: good, actual: good
test("test2", 1); ---expected: good, actual: good
test("test3", true, 1); ---expected: good, actual: good

test("test", 1); ---expected: bad, actual: good
test("test2", "string"); ---expected: bad, actual: good

test("test", true, 2) ---expected: bad, actual: bad
test("test3", "string"); ---expected: bad, actual: bad
test("test3", "string", 1); ---expected: bad, actual: bad
test("test3", true); ---expected: bad, actual: bad
```

I get the following errors:

With these overloads I would of expected the type to be equivalent to this:
```
{
param1: "test"
param2: string
} | {
param1: "test2"
param2: number
} | {
param1: "test3"
param2: boolean
param3: number
}
```
However, it is actually equivalent to:
```
{
param1: "test" | "test2"
param2: string | number
} |
{
param1: "test3"
param2: boolean
param3: number
}
```

首先重現 issue 中的多載範例，並追蹤 language server 對多載函式呼叫的型別檢查路徑。修正完成的標準是：引數型別和引數數量一樣能夠縮小多載範圍，接受所示的三個有效呼叫，並拒絕所示的不相符呼叫。

由索引模型根據 Issue 內容生成。