[FEA] Establish RAFT API contract

[cjnolet]

Tracking issue for updating the public API functions to adhere to the agreed-upon contract. This includes the ongoing refactor work kicked off by @divyegala.

• Add handle and remove explicit stream
• Use common storage / representation formats
• Consistency in ordering of arguments (ins vs outs, etc...)

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[github-actions]

This issue has been labeled inactive-30d due to no recent activity in the past 30 days. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed. This issue will be labeled inactive-90d if there is no activity in the next 60 days.

[cjnolet]

Marking the subtasks done here since we already have alignment on them. Remaining work will be completed in #535

[github-actions]

This issue has been labeled inactive-30d due to no recent activity in the past 30 days. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed. This issue will be labeled inactive-90d if there is no activity in the next 60 days.

[github-actions]

This issue has been labeled inactive-90d due to no recent activity in the past 90 days. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed.