feat: add aria snapshot utilities

[hi-ogawa]

• Required by feat: support aria snapshot vitest-dev/vitest#9668

I structured new code in a following way:

 src/aria/
 ├── folk/                        ← fork of Playwright, mirror its paths
 │   ├── injected/
 │   │   └── ariaSnapshot.ts      ← generateAriaTree, toAriaNode, renderAriaTree
 │   │                              imports roleUtils/domUtils from ivya
 │   └── isomorphic/
 │       └── ariaSnapshot.ts      ← parseAriaSnapshot, KeyParser, types,
 │                                  matchesNode, containsList, listEqual
 └── index.ts                    ← `ivya/aria` exports
 └── match.ts                     ← vitest-specific glue:
                                    three-way merge layer (mergeNode,
                                    mergeChildLists, pairChildren),
                                    regex-transparent diffing,

The documentation on Aria format is added as a dedicated page /guide/browser/aria-snapshots.md in

• feat: support aria snapshot vitest-dev/vitest#9668

[sheremet-va]

Do we need a separate folder? ivya is a fork of injected already

[hi-ogawa]

Putting all inside src/aria was somewhat simpler. What do you suggest? flat out under src/ariaXxx.ts?

[hi-ogawa]

I need to go through this algorithm more carefully. Seems like there's some slop 🤖