feat: Implement LegacyLinkAdapter between old and new 'core' links (#22202)

Part 2 of 4 to fix:
MetaMask/mobile-planning#2343

https://consensyssoftware.atlassian.net/jira/polaris/projects/MWMR/ideas/view/8845676?selectedIssue=MWMR-10

Previous Part: #21869

## Description

This PR adds `LegacyLinkAdapter`, a bidirectional adapter that bridges
the new `CoreUniversalLink` format (from PR #XXXX) with the existing
legacy deep link handlers. This is the second PR in Phase 1 of the deep
link consolidation project.

### Context
The current deep link system has routing logic fragmented across
multiple files with nested switch-case statements. This adapter enables
gradual migration to a unified routing system while maintaining 100%
backward compatibility with existing handlers.

### What Changed
- **Created `LegacyLinkAdapter`** with bidirectional conversion methods:
- `toLegacyFormat()` - Converts `CoreUniversalLink` to legacy `urlObj` +
`params` format
- `fromLegacyFormat()` - Creates `CoreUniversalLink` from legacy URL
strings
- `extractActionParams()` - Extracts action-specific paths and query
parameters
- `toProtocolUrl()` - Converts links between protocols (metamask://,
https://, ethereum://, dapp://)
- `shouldUseNewSystem()` - Feature flag system for gradual rollout
(currently disabled for all actions)
- `wrapHandler()` - Wraps legacy handlers to accept `CoreUniversalLink`

- **Added comprehensive test coverage** (23 test cases):
  - Format conversion tests
  - Parameter handling (including SDK params)
  - Protocol conversions
  - Edge cases (null/undefined values, empty paths)

### Why This Approach
- **Non-breaking**: No changes to existing deep link handlers in this PR
- **Gradual migration**: `shouldUseNewSystem()` allows action-by-action
rollout
- **Type-safe**: Full TypeScript coverage with proper type guards
- **Testable**: All adapter methods are pure functions with
comprehensive tests

### Dependencies
None

### How to Test
- Only automated tests at this time since this functionality is not
actually "enabled" in the app

---

## Changelog

### Added
- Added `LegacyLinkAdapter` for bidirectional conversion between new
`CoreUniversalLink` format and legacy deep link handlers
- Added migration strategy with `shouldUseNewSystem()` feature flag for
gradual rollout


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Introduce LegacyLinkAdapter for bidirectional conversion between new
core links and legacy handlers, add protocol/path utilities and tests,
and map `ACTIONS.PERPS_MARKETS` in the normalizer.
> 
> - **Deeplink Adapter**:
>   - Implement `LegacyLinkAdapter` with:
> - `toLegacyFormat` / `fromLegacyFormat` for bidirectional conversion
between `CoreUniversalLink` and legacy `urlObj` + `params`.
>     - `wrapHandler` to adapt legacy handlers to core links.
>     - `extractActionParams` to derive action path/query params.
> - `toProtocolUrl` to convert links across `metamask`, `https`,
`ethereum`, and `dapp`.
>     - `shouldUseNewSystem` feature-flag list (currently empty).
> - **Normalizer**:
> - Add `ACTIONS.PERPS_MARKETS` → `perpsMarketsPath` to
`ACTION_PATH_MAP` in `CoreLinkNormalizer`.
> - **Tests**:
> - Add `LegacyLinkAdapter.test.ts` covering conversions, param handling
(incl. SDK and custom params), protocol conversions, empty/edge cases,
and handler wrapping.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
d81867b. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: smilingkylan

app/core/DeeplinkManager/CoreLinkNormalizer.ts

@@ -32,6 +32,7 @@ export class CoreLinkNormalizer {
     [ACTIONS.ONBOARDING]: 'onboardingPath',
     [ACTIONS.CREATE_ACCOUNT]: 'createAccountPath',
     [ACTIONS.DEPOSIT]: 'depositCashPath',
+    [ACTIONS.PERPS_MARKETS]: 'perpsMarketsPath',
   };
 
   /**