Bounties Pallet to FrameV2

[ferrell-code]

relates: #7882

Following the upgrade guidelines here: https://crates.parity.io/frame_support/attr.pallet.html#upgrade-guidelines.

⚠️ Breaking Change ⚠️

From https://crates.parity.io/frame_support/attr.pallet.html#checking-upgrade-guidelines

storages now use PalletInfo for module_prefix instead of the one given to decl_storage: Thus any use of this pallet in construct_runtime! should be careful to update name in order not to break storage or to upgrade storage (moreover for instantiable pallet). If pallet is published, make sure to warn about this breaking change.

So users of the Bounties pallet must be careful about the name they used in construct_runtime!. Hence the runtime-migration label, which might not be needed depending on the configuration of the Bounties pallet. Since the old version was using Treasury in storage, it is probably safe to say all users of Bounties pallet must migrate.

Polkadot and Kusama both use the name Bounties in construct_runtime. They must be both migrated from the current pallet prefix of Treasury. see companion PR

polkadot companion: paritytech/polkadot#3704

[ferrell-code]

Not exactly sure how to test if this does indeed migrate the storage correctly, may need a pointer on that

[gui1117]

Looks good to me, I'll test the runtime migration on polkadot/kusama using try-runtime when reviewing the companion

[gui1117]

bot merge

[ghost]

Trying merge.