Split Polymesh chain from Polkadot impl.

[Neopallium]

Description

Split Polymesh support out of the Polkadot Rust impl into its own crate and fix permissions encoding.

How to test

Run Rust, C++, iOS, Android tests.

Types of changes

• Moves Polymesh support into its own coin and removes support from the Polkadot impl.
• Add correct support for permissions in the join identity authorization.
• Add support for leave identity transaction.
• Refactor batching support to allow batching any set of calls and support the different batch types (stop on first error, atomic, optimistic).
• Add ToScale support for String, BTreeSet, BTreeMap.
• Allow impl_enum_scale enums to re-use the same variant index for multiple variants, to support backwards/forwards compatibility (the spec/transaction versions can be used to encode the correct variant).

Checklist

• Create pull request as draft initially, unless its complete.
• Add tests to cover changes as needed.
• Update documentation as needed.
• If there is a related Issue, mention it in the description.

If you're adding a new blockchain

• I have read the guidelines for adding a new blockchain.