[python] move parse input functions to input_parser.py

[sindhuvahinis]

Description

Brief description of what this PR is about

• If this change is a backward incompatible change, why must this change be made?
• Interesting edge cases to note here

[siddvenk]

can you rebase with master? i merged the 3p changes earlier and those should be incorporated

[sindhuvahinis]

can you rebase with master? i merged the 3p changes earlier and those should be incorporated

Got it, Done!