Add ability for users to submit group proposals for credit class updates

[ryanchristo]

Is your feature request related to a problem? Please describe.

Currently there is no way to submit a group proposal from the marketplace application.

Describe the solution you'd like

If a user is logged in to an account that is a member of a group and one of the decision policy accounts within the group is the admin of the credit class, the user should be able to view the edit credit class pages and submit a group proposal to update the credit class.

Describe alternatives you've considered (optional)

Additional context (optional)

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[ryanchristo]

Per discussion with @blushi, this would likely be dependent on having an official version of regen-js api package with amino support fully tested and working for all messages used within the application. We could do without it but it would likely create more work down the road. Marking this blocked with dependency.