Related to - https://issues.jboss.org/browse/WINDUP-2314 (configuration wizard mock-up)

We need to implement the 'RHAMT: Edit existing configuration' wizard flow. This will walk the user through the necessary wizard pages for editing an existing configuration.

The high-level flow looks like this (triggered from a keybinding command):

RHAMT: Edit existing Configuration -> Choose configuration from a drop-down list of existing configurations -> Name -> Input -> Source -> Target -> Save or Run

This functionality + look and feel will be identical to that of the 'RHAMT: Create Configuration' wizard, except it will have an extra step at the beginning for selecting the configuration to edit, and the wizard pages will be populated with the existing values of the configuration being edited.

If 'Save' is chosen, the newly created configuration can be referenced later on using the 'RHAMT: Edit existing Configuration' or 'RHAMT: Run existing Configuration'.