Improve data type analysis for arbitrary values

[RobinMalfait]

This PR fixes an issue with incorrect splitting of arbitrary values and therefore improving the data type detection so that we require fewer type hints.

The original RegEx did mostly what we want, the idea is that we wanted to split by a , but one that was not within (). This is useful when you define multiple background colors for example:

<div class="bg-[rgb(0,0,0),rgb(255,255,255)]"></div>

In this case splitting by the regex would result in the proper result:

let result = [
  'rgb(0,0,0)',
  'rgb(255,255,255)'
]

Visually, you can think of it like:

    ┌─[./example.html]
    │
∙ 1 │   <div class="bg-[rgb(0,0,0),rgb(255,255,255)]"></div>
    ·                       ──┬── ┬    ─────┬─────
    ·                         │   │         ╰─────── Guarded by parens
    ·                         │   ╰───────────────── We will split here
    ·                         ╰───────────────────── Guarded by parens
    │
    └─

We properly split by , not inside a (). However, this RegEx fails the moment you have deeply nested , values or an ( is seen at the right of the current position. If you have the following example:

<div class="bg-[rgba(0,0,0,var(--alpha))]"></div>

Visually, this is what's happening:

    ┌─[./example.html]
    │
∙ 1 │   <div class="bg-[rgba(0,0,0,var(--alpha))]"></div>
    ·                         ┬ ┬ ┬
    ·                         ╰─┴─┴── We accidentally split here
    │
    └─

This is because on the right of the ,, the first paren is an opening paren ( instead of a closing one ).

I'm not 100% sure how we can improve the RegEx to handle that case as well, instead I wrote a small splitBy function that allows you to split the string by a character (just like you could do before) but ignores the ones inside the given exceptions. This keeps track of a stack to know whether we are within parens or not.

Visually, the fix looks like this:

    ┌─[./example.html]
    │
∙ 1 │   <div class="bg-[rgba(0,0,0,var(--alpha)),rgb(255,255,255,var(--alpha))]"></div>
    ·                         ┬ ┬ ┬             ┬       ┬   ┬   ┬
    ·                         │ │ │             │       ╰───┴───┴── Guarded by parens
    ·                         │ │ │             ╰────────────────── We will split here
    ·                         ╰─┴─┴──────────────────────────────── Guarded by parens
    │
    └─