chore: Move ChangeOwnership OwnershipMessageTypeFlags to an enum (#3648)

## Purpose of this PR
Swaps the `m_OwnershipMessageTypeFlags` from a bitfield to an enum as
the field is being used like an enum.

### Jira ticket
_Link to related jira ticket ([Use the smart
commits](https://support.atlassian.com/bitbucket-cloud/docs/use-smart-commits/)).
Short version (e.g. MTT-123) also works and gets auto-linked_

### Changelog
[//]: # (updated with all public facing changes - API changes, UI/UX
changes, behaviour changes, bug fixes. Remove if not relevant.)

- Changed: Internal representation of ChangeOwnershipMessage now uses an
enum rather than a bitfield.


## Documentation

- No documentation changes or additions were necessary.

## Testing & QA (How your changes can be verified during release
Playtest)

Can be playtested with the Astroids Ownership demos.

<!-- Add any performance testing results here if relevant. -->

### Functional Testing
[//]: # (If checked, List manual tests that have been performed.)
_Manual testing :_
- [ ] `Manual testing done`

_Automated tests:_
- [x] `Covered by existing automated tests`
- [ ] `Covered by new automated tests`

_Does the change require QA team to:_

- [ ] `Review automated tests`?
- [ ] `Execute manual tests`?
- [ ] `Provide feedback about the PR`?

If any boxes above are checked the QA team will be automatically added
as a PR reviewer.

## Backports

Performance improvement is only required to be in 2.x

Author: EmandM

com.unity.netcode.gameobjects/Runtime/Core/NetworkObject.cs

@@ -785,13 +785,13 @@ public OwnershipRequestStatus RequestOwnership()
             // Otherwise, send the request ownership message
             var changeOwnership = new ChangeOwnershipMessage
             {
+                ChangeMessageType = ChangeOwnershipMessage.ChangeType.RequestOwnership,
                 NetworkObjectId = NetworkObjectId,
                 OwnerClientId = OwnerClientId,
                 ClientIdCount = 1,
                 RequestClientId = NetworkManager.LocalClientId,
                 ClientIds = new ulong[1] { OwnerClientId },
                 DistributedAuthorityMode = true,
-                RequestOwnership = true,
                 OwnershipFlags = (ushort)Ownership,
             };
 
@@ -866,18 +866,18 @@ internal void OwnershipRequest(ulong clientRequestingOwnership)
             else
             {
                 // Otherwise, send back the reason why the ownership request was denied for the clientRequestingOwnership
-                /// Notes:
-                /// We always apply the <see cref="NetworkManager.LocalClientId"/> as opposed to <see cref="OwnerClientId"/> to the
-                /// <see cref="ChangeOwnershipMessage.OwnerClientId"/> value as ownership could have changed and the denied requests
-                /// targeting this instance are because there is a request pending.
-                /// DANGO-TODO: What happens if the client requesting disconnects prior to responding with the update in request pending?
+                // Notes:
+                // We always apply the <see cref="NetworkManager.LocalClientId"/> as opposed to <see cref="OwnerClientId"/> to the
+                // <see cref="ChangeOwnershipMessage.OwnerClientId"/> value as ownership could have changed and the denied requests
+                // targeting this instance are because there is a request pending.
+                // DANGO-TODO: What happens if the client requesting disconnects prior to responding with the update in request pending?
                 var changeOwnership = new ChangeOwnershipMessage
                 {
+                    ChangeMessageType = ChangeOwnershipMessage.ChangeType.RequestDenied,
                     NetworkObjectId = NetworkObjectId,
                     OwnerClientId = NetworkManager.LocalClientId, // Always use the local clientId (see above notes)
                     RequestClientId = clientRequestingOwnership,
                     DistributedAuthorityMode = true,
-                    RequestDenied = true,
                     OwnershipRequestResponseStatus = (byte)response,
                     OwnershipFlags = (ushort)Ownership,
                 };
@@ -1063,10 +1063,10 @@ internal void SendOwnershipStatusUpdate()
 
             var changeOwnership = new ChangeOwnershipMessage
             {
+                ChangeMessageType = ChangeOwnershipMessage.ChangeType.OwnershipFlagsUpdate,
                 NetworkObjectId = NetworkObjectId,
                 OwnerClientId = OwnerClientId,
                 DistributedAuthorityMode = true,
-                OwnershipFlagsUpdate = true,
                 OwnershipFlags = (ushort)Ownership,
             };