Support parsing multi-line union with comments

[rhys-vdw]

/***
 * @param someValues
 * | 1 # One
 * | 2 # Two
 * | 3 # Three
 * @function foo
 */

Alternative syntax:

---@alias Foo
---Hello
---| "H"
---Goodbye
---| "G"

[rhys-vdw]

This the more complicated case where we have a @param with multiline type description per-line and then a description for the param itself at the end.

---@param foo
---Hello
---| "H"
---Goodbye
---This could be two lines.
---| "G"
---This is foo.
local function bar(foo) end

Note that whitespace is valid before |