omitExtraData drops value of field whose identifier contains a dot "."

[JakobEdding]

Prerequisites

• I have read the documentation;
• In the case of a bug report, I understand that providing a SSCCE example is tremendously useful to the maintainers.
• Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue.

Description

See playground example

When omitExtraData is enabled, rjsf drops the value of a nested field for which the identifier contains a dot ., submit. This is unexpected behavior. In case the fields are also required, this leads to failure of form submission down the road. You can see this if you open the example and submit the form right away.

Note that the value of level.1.property seems to not be dropped, so there it works as expected.

Might be related to #2036

Steps to Reproduce

See playground example (same as above)

1. Turn on "omit extra data"
2. Add an object to the schema and another object as child.
3. Add a required field with name level.2.property and type string to the lower-level object from before.
4. Fill in dummy values in the form.
5. Submit the form.

Expected behavior

Form is submitted without errors.

Actual behavior

Form submission fails, field level.2.property is marked as required indicating that its value is empty.

Version

3.2.1

[v1ack]

still actual for version 5

[v1ack]

How it works now:

1. Form.getFieldNames gets a list of valid paths, ["dict1.field", "dict.2.field"]
2. Form.getUsedFormData uses loadash.pick to get values with paths from p.1 from formData

As I understood, we can fix it by making Form.getFieldNames return string[][] instead of string[], lile [["dict1", "field"], ["dict.2", "field"]]
It's valid for loadash.pick sources, but invalid for loadash.pick type annotations
@heath-freenome what do you think?