feat: check if allowance is needed

[sebastiendan]

Description

This PR makes ERC20 allowance approval conditional to the absence of existing large enough allowance. Thanks to this new feature, an ERC20 token transfer across subnet can be reduced in most cases to one single transaction.

Fixes TOO-275

Additions and Changes

New feature (non-breaking change which adds functionality)

• The useApproveAllowance hook now exposes a getCurrentAllowance callback that can be used to verify if a new allowance is needed

Breaking changes

• useApproveAllowance is renamed to useAllowance

PR Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added or updated tests that comprehensively prove my change is effective or that my feature works