[Feature Request] Intersection types

I apologize if this request has been reported before, I couldn't find any.
It would be great to be able to explicitly differentiate between union types and intersection types
e.g.
```lua
--- @class A
local a = {foo = 1}

--- @class B
local b = {bar = "hello"}

--- @param aOrB A | B
--- @param aAndB A & B
local function someFunc(aOrB, aAndB) end

someFunc(a, a) -- no warning, but 2nd argument should give a warning

--- @param a A
local function someOtherFunc(a) end

--- @type A | B -- would prefer to use A & B and not have any warnings
local aAndB = {foo = 1, bar = "hello"}
someOtherFunc(aAndB) -- Cannot assign `A|B` to parameter `A`. - `B` cannot match `A` - Type `B` cannot match `A` Lua Diagnostics. (param-type-mismatch)
```

While it's possible to use an explicit class with inheritance as a workaround, this is not always viable, especially when using dynamic types with generics
```lua
--- @class C: A, B
local c = {foo = 1, bar = "hello"}
someOtherFunc(aAndB) -- no warning

-- not viable when using something like this
--- @generic T1, T2
--- @param tbl1 T1
--- @param tbl2 T2
--- @return T1 | T2 -- would like to use T1 & T2 instead to avoid the warnings
local function merge(tbl1, tbl2) end

someOtherFunc(merge(a, b)) -- Cannot assign `A|B` to parameter `A`. - `B` cannot match `A` - Type `B` cannot match `A` Lua Diagnostics. (param-type-mismatch)
```

The suggested syntax `A & B` for intersection types and `A | B` for union types matches several other languages, such as TypeScript and PHP.

Edit: another workaround is to enable [luals.github.io/wiki/settings#typeweakunioncheck](https://luals.github.io/wiki/settings/#typeweakunioncheck). This has its own downsides, but may be helpful for people trying to avoid the `param-type-mismatch` warnings

No implementation files or tests are named. Start by tracing how Lua annotations represent unions and how the param-type-mismatch diagnostic handles them, then compare behavior with the A & B, A | B, and generic merge examples; done means intersection annotations avoid the demonstrated false warnings while unions retain their current checks.

Written by the indexing model from the issue text.