Refactors the `ɵɵcontrolCreate` and `ɵɵcontrol` instructions to delegate control logic to the forms package via new `ɵngControlCreate` and `ɵngControlUpdate` lifecycle hooks. Previously, the logic for binding form state to native elements and custom controls was hardcoded within `@angular/core`.
**Compiler Changes:**
- Introduces a new compilation phase `specializeControlProperties` (in `control_directives.ts`).
- This phase detects properties named `formField` and specializes them into `ControlCreate` and `Control` IR opcodes.
- These opcodes emit `ɵɵcontrolCreate` and `ɵɵcontrol` instructions, respectively.
**Runtime Changes:**
- `ɵɵcontrolCreate` acts as the creation phase. It locates the control directive and invokes its `ɵngControlCreate` method.
- `ɵɵcontrol` acts as the update phase, and invokes the control directive's `ɵngControlUpdate` method (if present).
- Introduces a `passThroughInput` configuration in `ControlFeature`. This specifies the input name (e.g., `formField`) that triggers the control. If the runtime detects that this input is bound to multiple targets (e.g., the `FormField` directive *and* the host component), the control is flagged as "pass-through". In this state, `ɵngControlCreate` returns a no-op update function, deferring responsibility to the other consumer (e.g., the component managing the field itself).
**Forms Changes:**
- `FormField` directive implements `ɵngControlCreate` and `ɵngControlUpdate`.
- Inside this hook, `FormField` determines the type of control it is attached to (Native, CVA, or Custom Signal Control) and delegates to the appropriate handler (`nativeControlCreate`, `cvaControlCreate`, or `customControlCreate`).
- Consolidates all form binding logic within `@angular/forms/signals`, enabling support for new `FormValueControl` and `FormCheckboxControl` interfaces.
- Reorganizes the codebase by moving `FormField` from `api/` to `directive/` and splitting the binding logic into semantic pieces:
- `control_native.ts`, `control_cva.ts`, and `control_custom.ts` contain the specific handlers for each control type.
- `native.ts` and `select.ts` provide helpers for native element discovery and select-specific synchronization.
- `bindings.ts` manages the tracking and application of property/attribute bindings.
This PR adds the ability to manually register a binding with the
`FormField` directive. This is useful for a lower-level implementation
that takes the field tree as an `input()` rather than relying on the
automatic binding from `FormUiControl`.
