Improve secondary key permissions.

[Neopallium]

changelog

new features

• Split secondary key permissions out of Identity.KeyRecords to allow for more efficient permissions checks.

modified external API

• Changed Identity.KeyRecords storage type to only hold the key type (primary, secondary, multisig) and the DID/AccountId. Secondary key permissions have been split out into storage Identity.KeyExtrinsicPermissions, Identity.KeyAssetPermissions, and Identity.KeyPortfolioPermissions.
• Renamed type DispatchableName to ExtrinsicName and change it to wrap a String instead of raw bytes Vec<u8>.
• Changed PalletName to wrap a String instead of raw bytes Vec<u8>.
• Changed type PalletPermissions to remove the pallet_name field (pallet name is used as a key the new ExtrinsicPermissions type).
• The extrinsic permissions in type Permissions has been changed to a new type ExtrinsicPermissions which uses maps instead of sets.
• Storage value ExternalAgents.GroupPermissions has changed since the extrinsic permissions uses maps instead of sets now.

modified events

• Any event containing a Permissions value will have changed (the extrinsic permissions are stored as a map instead of a set).

other

• The return type of identity RPC endpoints get_key_identity_data and get_did_records has changed, since the Permissions type now uses a map instead of a set for extrinsic permissions.

[Neopallium]

Migrations will be done in a different PR to be based off PR #1699 to avoid major conflicts.