Cherry-picks for 2.10.23-RC.1

[neilalexander]

Includes the following:

• https://github.com/nats-io/nats-server/pull/5115
• https://github.com/nats-io/nats-server/pull/6019
• https://github.com/nats-io/nats-server/pull/6039
• https://github.com/nats-io/nats-server/pull/6034
• https://github.com/nats-io/nats-server/pull/6043
• https://github.com/nats-io/nats-server/pull/6042
• https://github.com/nats-io/nats-server/pull/6047
• https://github.com/nats-io/nats-server/pull/6049
• https://github.com/nats-io/nats-server/pull/6050
• https://github.com/nats-io/nats-server/pull/6052
• https://github.com/nats-io/nats-server/pull/6053

Signed-off-by: Neil Twigg neil@nats.io