xxnetwork runtime 204

Created by: bernardo-xxnet

Client side refactor:

• Remove phoenixx runtime
• Rename protonet to canary
• Create runtime-common for all configuration values common to both runtimes
• Use features in order to reduce final size by removing canary runtime when compiling release binary
• Fix all tests and try-runtime compilation

Runtime changes:

• Staking pallet adding custody to Exposure
• Payout now uses exposure.total + exposure.custody as denominator when computing rewards
• Staking migration from 7.0.0 to 7.5.0 will trigger on mainnet in order to add custody of 0 to all existing Exposure structs