…ets to display seconds if needed (tucksaun)This PR was squashed before being merged into the 2.3 branch (closes#10777).Discussion----------[Form] Automatically add step attribute to HTML5 time widgets to display seconds if needed| Q             | A| ------------- | ---| Bug fix?      | yes| New feature?  | no| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets |#9976,#10203| License       | MIT| Doc PR        | noneSame issue as#9976 and#10203: when you add a `time` field to a form with options `single_text` (so HTML5) and `with_seconds`, the generated input does not contain the `step` attribute, therefore the browser does not show them, leading to an error at the submit because of an invalid format.Compared to#9976/#10203:* Unit testable* Available directly in the component* Available in other templating format than twig* Still able to customise the step attribute by handCommits-------a379298 [Form] Automatically add step attribute to HTML5 time widgets to display seconds if needed