Add events for initial aggregate pool fees

[EndymionJkb]

Description

Add events to track the initial aggregate fee percentages for pools. Otherwise, there would be no indication (off-chain) that a pool was registered as protocol fee exempt.

Type of change

• Bug fix
• New feature
• Breaking change
• Dependency changes
• Code refactor / cleanup
• Optimization: [ ] gas / [ ] bytecode
• Documentation or wording changes
• Other

Checklist:

• The diff is legible and has no extraneous changes
• Complex code has been commented, including external interfaces
• Tests have 100% code coverage
• The base branch is either main, or there's a description of how to merge

Issue Resolution

Resolves #1247

[jubeira]

Thanks @EndymionJkb; this looks good.

Adding @mendesfabio to the loop.

[joaobrunoah]

LGTM! We don't set the aggregate fee percentages after initialization, so using the same events for the initial value and the fee percentage setters doesn't make sense.