…wig functions

This PR was merged into the master branch.Discussion----------[Form] Deprecated bind() and isBound() in favor of submit() and isSubmitted()| Q             | A| ------------- | ---| Bug fix?      | no| New feature?  | no| BC breaks?    | yes (*)| Deprecations? | yes| Tests pass?   | yes| Fixed tickets |#5493| License       | MIT| Doc PR        | TODOThis change was discussed for a while in#5493. **(*)** It breaks BC *only for people who implemented* `FormInterface` *manually* (not a lot, so I hope). These can fix the problem by simply renaming `bind()` and `isBound()` in their implementation to `submit()` and `isSubmitted()`.The main rationale is that with the request handlers introduced in#6522, people won't be confronted with the term "binding" anymore. As such, `isBound()` will be a very strange name to new users that have never used `bind()` manually.See this code sample as example:```php$form = $this->createForm(...);$form->handleRequest($request);// Imagine you have never heard about bind() or binding. What does this mean?if ($form->isBound()) {    // ...}```In reality, `bind()` submits a form. Where-ever I renamed "bind" to "submit" in the comments, "submit" made actually much more sense. So it does in the code sample above:```php$form = $this->createForm(...);$form->handleRequest($request);// Aha!if ($form->isSubmitted()) {    // ...}```Also when using `submit()` directly, the code makes much more sense now:```php$text = $this->createForm('text');$text->submit('New Value');```For current users, the current naming will be supported until 3.0.Commits-------41b0127 [Form] Deprecated bind() and isBound() in favor of submit() and isSubmitted()