[P2] util.js: relocate snap helpers

**Parent Epic:** [#44552 — `util.js` decomposition](https://github.com/MetaMask/metamask-extension/issues/44552)
**Source:** `ui/helpers/utils/util.js`
**Size:** L

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## Problem

`getSnapName` (fan-out ~20), `getSnapRoute` (UI-coupled via `SNAPS_VIEW_ROUTE`), `getDedupedSnaps`, `getFilteredSnapPermissions`.

## Solution

- `getSnapRoute` → `ui/helpers/utils/snaps.ts` (must stay UI-side — route constant).
- `getSnapName`, `getDedupedSnaps`, `getFilteredSnapPermissions` → `shared/lib/snaps/snaps.ts`.
- Codemod the ~20 `getSnapName` sites (own the largest rewrite here).

## Acceptance Criteria

- [ ] Snap helpers relocated to the named modules; originals deleted; ~20 `getSnapName` sites rewired (codemod). Tests green.

Start with ui/helpers/utils/util.js and compare the named destinations ui/helpers/utils/snaps.ts and shared/lib/snaps/snaps.ts. Trace the approximately 20 getSnapName call sites, then relocate the helpers, rewire those sites with a codemod, and run the test suite to confirm the acceptance criteria are met.

Written by the indexing model from the issue text.