Improve error message when remote service wizard is used without remote service workspace template

[scottslewis]

If the user installs the ECF Remote Services feature in bndtools 7.2+ and uses the service wizard to create a remote service, the following error message will occur, because the template will not be found in the existing workspace:

The fix for this is to create a new bndtools workspace using the ECF Remote Services workspace template, which has the necessary remote services templates.

The fix for this will be to enhance the error message to explain the necessary steps (create a new bndtools workspace, with the ECF Remote Services workspace template.

[chrisrueger]

for completeness this was the exception I got:

Caused by: java.lang.IllegalArgumentException: Path for project must have only one segment but has 0: /
    at org.eclipse.core.runtime.Assert.isLegal(Assert.java:68)
    at org.eclipse.core.internal.resources.WorkspaceRoot.getProject(WorkspaceRoot.java:169)
    at org.eclipse.jdt.ui.wizards.NewJavaProjectWizardPageTwo.updateProject(NewJavaProjectWizardPageTwo.java:215)
    at org.eclipse.jdt.ui.wizards.NewJavaProjectWizardPageTwo.performFinish(NewJavaProjectWizardPageTwo.java:460)
    at org.eclipse.jdt.internal.ui.wizards.JavaProjectWizard.finishPage(JavaProjectWizard.java:79)
    at org.bndtools.core.ui.wizards.service.NewBndServiceWizard.finishPage(NewBndServiceWizard.java:69)

But it could be that this exception appeared after finishing the wizard on the next page. But I guess same root cause