Add pallet-flow

[vovacha]

Pallet Flow migration.

DONE:

• Pallet Flow code migration.
• orml-currencies support.
• Fixed point arithmetic: CampaignFee.
• Mocks, tests.
• .editorconfig.

TODO:

• Benchmarks (blocked by Control pallet)

Next steps:

1. Merge Flow, Signal, Control feature branches.
2. Test everything together, update zero-protocol runtime.
3. Flow benchmarks, Signal benchmarks.
4. Control tests and benchmarks.
5. Hardening.

[2075]

@vovacha we could also collect those primitives which are gamedao specific in another primitives module in here.

[vayesy]

Suggested change

	pub type Timestamp = u64;
	use zero_primitives::{BlockNumber, Hash, Timestamp};

And use those variables here?

[vovacha]

I want to explicitly declare those types here to show that they could potentially differ from the actual runtime types from zero_primitives even if they are the same now.

[vayesy]

Can you also add a ToDo somewhere in the file to update storage objects and drop getters as we discussed earlier?

[vayesy]

You can store result of T::FundingCurrencyId::get() to some variable and use it instead, since this value is used in multiple places over the on_finalize hook.

[vovacha]

Thank you. Both getters refactoring, and this issue will be handled later during the hardening stage.