#4746: adjusted the send a tweet's maximum character limit to accomodate hashtags and via @code.

[eklavyamirani]

Modified the IFeedback service to provide the character limit that the feedback service supports.
Implemented this logic in TwitterFeedbackService to give the remaining characters after accommodating hashtags (modified to be an array now) and the VIA tag, if one exists.

Fixes #4746

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[msftclas]

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[joaomoreno]

Thanks! 👍