Enable liquidity providers

[gztensor]

Description

Introduce LP capability inspired by Uniswap v3. Adds a new pallet with the following extrinsics:

add_liquidity

Allows a user who owns some TAO and some Alpha stake to provide their TAO and/or Alpha stake as a liquidity position between low and high price of their choise. Other users will be able to consume this liquidity when they add or remove stake.

remove_liquidity

Removes user liquidity position and credits TAO and Alpha stake back to the user account (including accrued fees).

modify_position

Updates user liquidity position and:

• Credits TAO and Alpha to user account if liquidity is removed with accrued position fees
• Uses user TAO and Alpha stake (less accrued position fees) to increase position liquidity

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Breaking Change

New field in SubnetHyperparamsV2: user_liquidity_enabled: bool at the end of the struct.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run cargo fmt and cargo clippy to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[tutacrypto]

Hey @l0r1s @gztensor
Who should we ask for details about the implementation?
What's the main file(s) to look at?

[ales-otf]

Hey @l0r1s @gztensor Who should we ask for details about the implementation? What's the main file(s) to look at?

For details ask Greg (@gztensor) and you can refer to Uniswap V3 documentation. The entire implementation is done inside pallet-subtensor-swap (pallets/swap). And the most of it is inside of pallets/swap/src/pallet/impls.rs.

[ales-otf]

closes #1494