Feature: support FIXED GIVEN Padding

[penguinolog]

• GIVEN width for padding always produces FIXED render for FLOW wrapped widget

Checklist

• I've ensured that similar functionality has not already been implemented
• I've ensured that similar functionality has not earlier been proposed and declined
• I've branched off the master or python-dual-support branch
• I've merged fresh upstream into my branch recently
• I've ran tox successfully in local environment
• I've included docstrings and/or documentation and/or examples for my code (if this is a new feature)

[coveralls]

Pull Request Test Coverage Report for Build 7489846891

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 69.755%

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Totals
Change from base Build 7487648572:	0.05%
Covered Lines:	8240
Relevant Lines:	11902

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💛 - Coveralls