CP-14598 before after bind

[niden]

Hello!

• Type: new feature
• Link to issue: [NFR]: beforeBind and afterBind for Form #14598

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Added beforeBind and afterBind hook methods to Phalcon\Forms\Form. When defined on a form subclass, beforeBind(array $data, ?object $entity) runs at the start of bind() (returning false cancels the bind) and afterBind(?object $entity) runs after the data has been assigned. Both also fire when bind() is reached through isValid().
Thanks