This PR adds the ability to add a cap to the bitrate when starting an archive.

Description

You can add maxBitrate within the startArchive() method when adding an options array.

$archive = $openTok->startArchive($sessionId, ['maxBitrate' => 2000000]);

Motivation and Context

Parity with Video APIs

How Has This Been Tested?

StartArchive test has been modified.

Example Output or Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.