Fix filters for Doctrine embedded class fields

[Ang3]

Fixes #4245

Explanations
This fix replaces dots by underscore internally in the form and filters collection without change anything else.

Limitations

• For Doctrine embedded classes only (no association support, maybe you could create a traversable filter to apply joins)
• If you have two fields foo.bar (embedded) and foo_bar (not embedded), you might have some troubles.

[Ang3]

No reply and pull request #4882 inserted into the milestone 4.x.

I think a nested filter is not an efficient way because it breaks the logic of filters : it takes care about embedded class properties (mixed type) AND associations (the aim of the entity filter). Nevermind, the most important is to be able to use filters on embedded Doctrine classes: a very very very primary feature and without discuss about.

[ksn135]

Geat work! 👍
It's looks more solid then #4882