The Ambassador Program on Polkadot Collectives Parachain

The Polkadot Ambassador Program has existed for a while; more
information can be found
[here](https://wiki.polkadot.network/docs/ambassadors).
In this PR, the program is being brought on chain.

### On Chain Structure
The on-chain program consists of nine ranks, divided into four
categories ([full
list](https://github.com/paritytech/cumulus/blob/c238fb26b75569a11abb57437fd14acd26e05f18/parachains/runtimes/collectives/collectives-polkadot/src/ambassador/mod.rs#L52)):
- Ambassadors (1-2 tiers)
- Senior Ambassadors (3-4 tiers)
- Head Ambassadors (5-7 tiers)
- Master Ambassadors (8-9 tiers)

Each rank has a corresponding `Origin` (e.g., `HeadAmbassadorsTier5` -
[full
list](https://github.com/paritytech/cumulus/blob/c238fb26b75569a11abb57437fd14acd26e05f18/parachains/runtimes/collectives/collectives-polkadot/src/ambassador/origins.rs#L35)),
which represents the collective voice of members of that rank and above.

### Referendum

The `AmbassadorReferenda` instance of [referenda
pallet](https://docs.rs/pallet-referenda/latest/pallet_referenda/)
consists of [nine
tracks](https://github.com/paritytech/cumulus/blob/c238fb26b75569a11abb57437fd14acd26e05f18/parachains/runtimes/collectives/collectives-polkadot/src/ambassador/tracks.rs#L51),
each corresponding to an `Origin`. A referendum taken on `senior
ambassador tier 4` track invites all members from rank 4 or above to
vote and commands `SeniorAmbassadors` `Origin`. Every member gets one
vote plus an additional vote for every excess rank. The referendum
proposal can be submitted by any member of a senior rank or above.

### Membership Management

Initial members will be brought on chain via migration, with subsequent
member management handled through the `AmbassadorCollective` instance of
[ranked collective
pallet](https://docs.rs/pallet-ranked-collective/latest/pallet_ranked_collective/).
Both `Root` and `FellowshipAdmin` `Origins`, commanded via public
Polkadot referendum, can promote or demote members to and from any rank.
Members themselves also have the power to promote or demote via its
referendum, with a senior member vote by the rank two above the new /
current rank - [full
configuration](https://github.com/paritytech/cumulus/blob/9ab6aa47063d7e8b67ddc10d9c136037f99c03a3/parachains/runtimes/collectives/collectives-polkadot/src/ambassador/mod.rs#L67).

### Content Management

The program's on-chain content is managed via the collectives content
pallet, allowing for setting its charter and making announcements. The
voice of head ambassadors have the authority to set the charter, while
announcements can be made by any senior rank member or through a
referendum among all members.

### Additional Functionality

The `AmbassadorCore` instance of [core fellowship
pallet](https://docs.rs/pallet-core-fellowship/latest/pallet_core_fellowship/)
decorates the ranked collectives pallet with features like salary
determination, activity/passivity registration, and the handling of
promotion and demotion periods. While the usage of this pallet is
optional in the first version, future updates will make it the exclusive
method for induction/promotion.

Periodic salaries in USDt, payable on Asset Hub, are introduced through
the [salary
pallet](https://docs.rs/pallet-salary/latest/pallet_salary/). This
requires induction into the ambassador core pallet.

Please for more information on the pallets' functionality refer to their
documentations.

### Next Steps:
- Migrate to seed the program members
- Mint ambassador NFT badges on Asset Hub when promoting
- Treasury pallet instance for the Ambassador Program

---------

Co-authored-by: Kian Paimani <[email protected]>
Co-authored-by: joe petrowski <[email protected]>