Fixes #498

This PR creates the following behaviors:

1. A Hot Code Replace failure will now prompt the user to "refresh" the debugger. This will result in the debugger being disconnected and reconnected
   2. A restart of the server from dev mode via the command line will result in the debugger being disconnected and reconnected when the server restarts (using whatever debug port dev mode chose)
   3. When in debug mode, the debugger is always on.... if disconnected (automatically or manually), it will always attempt to reconnect.

After reviewing, it seemed overkill to attempt to reconnect the debugger on every disconnect. This also created issues when intentionally disconnecting the debugger. In place of number 2 and 3 above, we are instead adding a "Connect Liberty Debugger" action to the Debug view context menu. If the debugger is disconnected (due to a restart of the server or manual disconnect), a user can now reconnect without having to stop and start the application via the Dashboard.

----- More Details ------

In the second rendition of the Liberty Tools debugger (prior to this PR), the debugger was combined with the Maven/devmode process into one launch configuration. This meant that the lifecycle of the two processes were tightly coupled causing undesired behavior. For example, a disconnect of the debugger triggered a full termination of the application running in Maven. 3 ways this disconnect could happen is either via a HCR failure, a restart of the server via devmode, or a manual disconnect via the debug view context menu.

This PR makes the following improvements:

1. A custom HCR failure dialog is presented to the user with an option to restart the debugger. This does so without a restart to the Maven/devmode process.
2. A new LibertyDebugTarget is used which overrides the default JDIDebugTarget disconnect behavior by not triggering a "terminate" of the launch (the root problem).
3. Introduces a "Connect Liberty Debugger" action to the debug view context menu.