Add Jetty support

[axelfontaine]

Currently with ktor + jetty, you can either

1. install no extensions

• clean transaction names
• no database info
• no coroutine info

2. install the coroutine extension:

• no transaction names (only Kotlin/Coroutine/jetty-call-handler and Coroutine/Kotlin/Coroutine/jetty-call-handler)
• clean database info
• coroutine info

3. install the coroutine and ktor extension:

• no transaction names (only Kotlin/Coroutine/jetty-call-handler and Coroutine/Kotlin/Coroutine/jetty-call-handler)
• clean database info
• coroutine info

None of these is ideal. Using the latest versions of agent and both extensions for all 3.