[Form] DateTimeToRfc3339Transformer use proper transformation exteption in reverse transformation
merged branch kibao/datetime-rfc3339-transformer (PR #7618)

This PR was merged into the 2.1 branch.

Discussion
----------

[Form] DateTimeToRfc3339Transformer use proper transformation exteption in reverse transformation

Handle _Exception_ throwed by DateTime constructor if an invalid date is passed.
Then throws proper transformation exception.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
-------

7fc429f [Form] DateTimeToRfc3339Transformer use proper transformation exteption in reverse transformation