Allow to capture Netty errors

[TecdocCatalogBackend]

We had the need to be able to capture netty errors and handle then, as this lib is opensource, we wanted to keep custom implementation details outside, so the lib would only allow to register a different exception handler, which by default if not specified will work the same way.

If it's relevant the main use case, was to be able to capture Connection Reset By Peer errors, and log then at a different level, other than error

[tpunder]

Hi Kevin,

Your branch doesn't compile on Scala 2.11:

sbt:fm-http> + compile
[info] Setting Scala version to 2.11.12 on 1 projects.
[info] Reapplying settings...
[info] set current project to fm-http (in build file:/private/var/tmp/fm-http/)
[info] compiling 69 Scala sources to /private/var/tmp/fm-http/target/scala-2.11/classes ...
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServer.scala:66:1: identifier expected but ')' found.
[error] ) extends Logging {
[error] ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServer.scala:199:2: ':' expected but eof found.
[error] }
[error]  ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServerApp.scala:139:5: illegal start of simple expression
[error]     )
[error]     ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServerApp.scala:192:3: ')' expected but '}' found.
[error]   }
[error]   ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServerOptions.scala:114:1: identifier expected but ')' found.
[error] ) {
[error] ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/HttpServerOptions.scala:116:3: ':' expected but eof found.
[error] }
[error]  ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/NettyHttpServerPipelineHandler.scala:66:1: identifier expected but ')' found.
[error] ) extends SimpleChannelInboundHandler[HttpObject] with Logging {
[error] ^
[error] /private/var/tmp/fm-http/src/main/scala/fm/http/server/NettyHttpServerPipelineHandler.scala:542:2: ':' expected but eof found.
[error] }
[error]  ^
[error] 8 errors found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 2 s, completed Apr 24, 2024, 7:56:28 AM

[tpunder]

Also, I usually test/build/publish with Java 11 for better compatibility. That probably makes the Policy deprecation warning/error go away.