Separate `snap_manageState` into separate functions `snap_getState`, `snap_setState`, and `snap_clearState`

[Mrtenz]

The snap_manageState API is a bit strange currently, because you have to specify an operation for each request. It's better if the method was separated into three separate methods:

• snap_getState, similar to the get operation.

  await snap.request({ method: 'snap_getState', params: { key: 'foo' } });

• snap_setState, similar to the update operation, whereparams is the new state.

  await snap.request({ method: 'snap_setState', params: { key: 'foo', value: 1 } });

• snap_clearState, similar to the clear operation.

  await snap.request({ method: 'snap_clearState' });

snap_manageState can be deprecated, and mapped internally to one of the methods above, depending on the operation.

Right now we only have one-to-one mappings for permissions to their respective JSON-RPC methods. In order to accomplish the above, while using a single permission, we need to have a way to map one-to-many, from a single storage permission to all the methods above.

[kenhkan]

From refinement:

• PermissionController work needed.
• Hassan to continue work next sprint.
• Make ourselves the CODEOWNERS for PermissionController, RateLimiterController, NotificationController

[kenhkan]

Hey team! Please add your planning poker estimate with Zenhub @ritave @hmalik88 @FrederikBolding @Mrtenz @GuillaumeRx @david0xd

[Mrtenz]

Done in #2916.