Netty: Implement httpOptions persistTimeout

[pnicolucci]

https://openliberty.io/docs/latest/reference/config/httpEndpoint.html

persistTimeout | A period of time with second precision | 30s | Amount of time that a socket will be allowed to remain idle between requests. This setting only applies if persistent connections are enabled. Specify a positive integer followed by a unit of time, which can be hours (h), minutes (m), or seconds (s). For example, specify 30 seconds as 30s. You can include multiple values in a single entry. For example, 1m30s is equivalent to 90 seconds. -- | -- | -- | --

The lack of this implementation causes various CTS tests to hang as they are reading from a socket and the socket never closes so the test just hangs until it times out around 2 hours later.

For example: https://github.com/jakartaee/platform-tck/blob/8.0.x/src/com/sun/ts/tests/servlet/api/javax_servlet_http/httpservletrequest40/Client.java#L290