feat(input_schema): datepicker allowAbsolute/allowRelative properties and validation

[MFori]

This PR introduce new input_schema properties allowAbsolute and allowRelative used when the editor property is set to datepicker:

• the schema.json is updated in the way, that properties allowAbsolute and allowRelative are valid only when editor is datepicker, allowAbsolute is considered as default and any of allowAbsolute or allowRelative is true
• value format validation
• unit tests for schema validation and value validation
• New datepicker with support for absolute and relative dates PR: https://github.com/apify/apify-core/pull/17465
• Docs PR: https://github.com/apify/apify-docs/pull/1227