This commit updates the signal forms API to use a consistent 'when' parameter for conditional rules and validators, replacing direct function arguments.
`FieldTree` was an unnecessarily specific type for the `[formField]`
input. It forced the directive to care about what _kind_ of `FieldTree`
was bound–specifically whether it was Reactive Forms compatible or not.
This made it difficult to author forms system-agnostic components with
passthrough `[formField]` inputs.
This completes the rename started in #66136. `[field]` is too generic of
a selector for the forms system to own, and likely to cause naming
collisions with existing components. Therefore it is being renamed to
`[formField]`
This will replace the `[field]` directive, since `[field]` is a very
generic name for signal forms to commandeer
refactor(forms): hook up `formField` directive in compiler
Hooks up the `formField` direcive to get the same treatment as the
`field` directive in the compiler.
apply updated formatting
SkyZeroZx