The mail message composer was reorganized to move some behind-the-scenes logic into shared models. This should make the composer easier to maintain and evolve without changing how users write messages today.

+ Create ComposerTextInputView model
+ Replace uses of useRef with useRefToModel
+ Replace use of useUpdate with useUpdateToModel
+ Remove dead code (ComposerTextInput._isEmpty)

Task-3001200.

The Belgian payroll commission import field has been updated to use Odoo’s newer interface technology. This keeps the feature aligned with the current platform and helps maintain a smoother, more reliable user experience without changing the business workflow.

This commit migrates the `binary_commission` field to owl.