refactor!: Add consolidated legacy method middleware

[rekmarks]

Explanation

Consolidates the bespoke makeMethodMiddlewareMaker implementations from the
MetaMask extension and mobile clients into a single legacy createMethodMiddleware
exported from @metamask/json-rpc-engine, and removes the unused permitted
method handlers from @metamask/permission-controller.

@metamask/json-rpc-engine

• Adds a legacy createMethodMiddleware that builds a JsonRpcEngine middleware
  from a record of handlers keyed by method name. Hooks are validated against the
  union of hookNames declared by the handlers (rejecting both missing and
  extraneous hooks), and incoming requests are dispatched by method.
• Handlers may declare actionNames and receive a per-handler delegated
  Messenger as the sixth argument to implementation, mirroring the v2
  createMethodMiddleware.
• The legacy and v2 versions share their hook selection / validation and
  messenger delegation utilities (assertExpectedHooks, selectHooks,
  createHandlerMessenger).
• The legacy export is deprecated in favor of the v2 createMethodMiddleware.
  It exists only to give the extension and mobile clients a consolidated
  migration target before they move to JsonRpcEngineV2.

@metamask/eip1193-permission-middleware (BREAKING)

• Reshapes the per-method exports (getPermissionsHandler,
  requestPermissionsHandler, revokePermissionsHandler) into the new
  MethodHandler format and consolidates them into a single methodHandlers
  export keyed by method name. The individual handler exports are removed.

@metamask/multichain-api-middleware (BREAKING)

• Reshapes the per-method exports (walletCreateSession, walletGetSession,
  walletInvokeMethod, walletRevokeSession) into the new MethodHandler
  format and consolidates them into a single methodHandlers export keyed by
  method name. The individual handler exports are removed.

@metamask/permission-controller (BREAKING)

• Removes the permitted RPC method handler modules (getPermissions,
  requestPermissions, revokePermissions) and the related
  permissionRpcMethods and PermittedHandlerExport exports. These were unused
  in practice. Replacement types are available in
  @metamask/json-rpc-engine@10.3.0.

References

• Related: Migrate JSON-RPC stack to JsonRpcEngineV2 #6327
  • We don't migrate anything to v2 in this PR, but it ought to make that migration simpler.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

---

Note

Medium Risk
Introduces new JSON-RPC dispatch middleware and reshapes multiple public package exports (breaking), so downstream integrations may break and runtime hook validation/dispatch paths could affect request handling.

Overview
Adds a deprecated legacy createMethodMiddleware export to @metamask/json-rpc-engine that dispatches requests by req.method, validates hooks (missing/extraneous), optionally delegates a per-handler messenger via declared actionNames, and normalizes thrown non-Error values into JSON-RPC internal errors.

Introduces breaking API shape changes in @metamask/eip1193-permission-middleware and @metamask/multichain-api-middleware by consolidating per-method exports into a single methodHandlers record keyed by method name, updating handlers to the new MethodHandler format, and adding tests that construct middleware from these handlers; wallet_createSession now requires a trackSessionCreatedEvent hook (nullable).

Removes unused permitted RPC method handler modules/types from @metamask/permission-controller (including permissionRpcMethods and PermittedHandlerExport) and updates v2 JSON-RPC engine utilities to centralize hook selection/validation and messenger delegation; changelogs and lint suppressions are updated accordingly.

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