[inputstream] support mime type by default for all inputstream addons

[phunkyfish]

Description

Mime type if available will be sent to inputstream addons.

Motivation and Context

Otherwise each inpustream addon needs to implement its own property for this purpose.

How Has This Been Tested?

OSX using inputstream.ffmpegdirect

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[AlwinEsch]

Yes, this makes sense and is OK to add.