Powertools v4: ideas, breaking changes and notes.

[leandrodamascena]

Discussion to add ideas, breaking changes and notes for Powertools v4.

[leandrodamascena]

Metrics - Add support for default dimensions on ColdStart metric captured with log_metrics decorator

We need to include default dimensions when creating ColdStart metric.

Original issue: #5237

[leandrodamascena]

Data Masking - Our current implementation is assuming that we need to pass provider_options for all actions like encrypt, decrypt and erase, which is wrong and forces us to keep unused variables in 2 functions due to erase doesn't have options provider. This also increase maintenance complexity. We need to fix this in V4

Reference: https://sonarcloud.io/project/issues?sinceLeakPeriod=true&issueStatuses=OPEN%2CCONFIRMED&pullRequest=5837&id=aws-powertools_powertools-lambda-python&open=AZTSVHRfHIq6zvFAvuD4

[leandrodamascena]

Logger - Child Logger

Customers can't change the log format and keys like location when working with Child loggers. We must fix it in v4.

Reference: #5412