Add debug port collision/failover capabilities to Liberty Tools debugger integration

It is possible to achieve a port collision by specifically specifying a debug port, (so if you specify the same one for two different runs), you collide.

Though the Liberty Tools Eclipse debugger integration selects a "random" port, it is conceivable also that this port gets used in the window btw. the time we select it and the time we are ready to launch the server from the LMP/LGP dev mode function.

The LMP/LGP function has failover support built into it, but Liberty Tools Eclipse does not currently take advantage of this. Partly we did this to allow for using an "external" install (e.g. for LMP, not a target/liberty/wlp install).. since the easiest way to do this would be to look at the target server.env, where LMP/LGP write the failover port into.

In some ways this is almost an enhancement on top of the current function, which will largely work in most cases, especially if a specific port is not specified more than once.

Start by tracing the Liberty Tools Eclipse debugger integration and the LMP/LGP dev mode launch path, then compare their existing failover behavior. Inspect how target server.env records the failover port and account for external installs; done means specified or selected debug ports handle collisions and fail over reliably.