Update Rule: frame-title-unique to ensure identical iframe serve same purpose

> Update: Instead of creating a new rule, will be update the rule `frame-title-unique`.

# identical-iframes-same-purpose

This rule checks that iframe elements with identical accessible names embed the same resource or equivalent resources.

## Tags
- wcag2
- wcag412

## Matches / Selector

- `iframe`
- which are in the same document tree
- which are included in the accessibility tree

## Checks

**all:**
- identical-frames-same-purpose
- `incomplete` : `Check that iframe have the same purpose, or are intentionally ambiguous`.
- `pass`: `There are no other iframe's with the same name, that go to a different URL`

- identical-frames-same-purpose-after
- all matching nodes in the results are processed to find any identical nodes (same accessible name) and verified if they resolve to the same resource. Nodes which do not satisfy to the same resource are marked as `incomplete`.

### References:
- [ACT Rule: Iframes with identical accessible names serve equivalent purpose](https://act-rules.github.io/rules/4b1c6c)