Allow to pass FFMPEG bitrate parameters #1247

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Problem

User story from Band on Discord:

I have a related use case. We are also publishing to Instagram via the ig-user/media API (https://developers.facebook.com/docs/instagram-api/reference/ig-user/media#reel-specifications). We’ve had a lot of flakiness with IG throwing vague errors for video uploads in the past, so we have validators that catch discrepancies between the IG specs and the video we are attempting to upload. While the test videos rendered by remotion seem to upload fine, The team is hesitant to remove any validators, since we can point to Instagram as being the source of the issues if we are matching their requirements. It would be convenient if I could add -ab 128 to the ffmpeg call so it passes our validation and everyone is happy.

Hacktoberfest Acceptance criteria

• Allow to customize -b:v and b:a parameters using a new option for stitchFramesToVideo() and renderMedia()
• If using renderMediaOnLambda(), the option should also be passed
• If using the npx remotion lambda render or the npx remotion render commands, new command line flags should be introduced to use the feature from the CLI as well.
• All APIs that accept the parameter should have their API page updated.