ktest: Ask for type of test when creating a new config

When no argument is supplied to ktest, or the config applied does
not exist and a new config is being created, instead of just using
the default test type, give the user an option to pick the test type
of either 'build, install, or boot'. Other options may be added later
but then those would require more questions as they require more
fields. But that's for another release of ktest to add that feature.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>