Add Cairto to Midi transpiler

[AryanGodara]

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Currently we support midi to cairo conversions, but not the other way round

Issue Number: Resolves #36

What is the new behavior?

Implementes cairo_struct_to_midi convertor function

• Updated Makefile with new endpoint
• Updated cli.py to accept a generic input_file instead of having a hardcoded midi_file as input
• Added functionality to be able to interconvert MIDI<>cairo

Does this introduce a breaking change?

• Yes
• No

The Makefile targets have been updated, so the README has been updated as well.

Other information