cli: Rework adhoc CLI parsing into a class structure

This adds:

VirtCLIArgument: a single foo=bar mapping
VirtOptionString: A collection of VirtCLIArguments, that parses the whole thing
VirtCLIParser: Represents a single cli option like --disk, --network, etc.

Centralizing this infrastructure opens up a lot of doors for future
improvements, like cli option introspection.

tests/clitest.py

@@ -425,12 +425,12 @@ c.add_valid("--vcpus sockets=2,threads=2")  # Topology only
 c.add_valid("--cpu somemodel")  # Simple --cpu
 c.add_valid("--cpu foobar,+x2apic,+x2apicagain,-distest,forbid=foo,forbid=bar,disable=distest2,optional=opttest,require=reqtest,match=strict,vendor=meee")  # Crazy --cpu
 c.add_valid("--numatune 1,2,3,5-7,^6")  # Simple --numatune
+c.add_valid("--numatune 1-3,4,mode=strict")  # More complex, parser should do the right thing here
 c.add_compare("--connect %(DEFAULTURI)s --cpuset auto --vcpus 2", "cpuset-auto")  # --cpuset=auto actually works
 c.add_invalid("--vcpus 32 --cpuset=969-1000")  # Bogus cpuset
 c.add_invalid("--vcpus 32 --cpuset=autofoo")  # Bogus cpuset
 c.add_invalid("--vcpus 20 --check-cpu")  # Over host vcpus w/ --check-cpu
 c.add_invalid("--cpu host")  # --cpu host, but no host CPU in caps
-c.add_invalid("--numatune 1-3,4,mode=strict")  # Non-escaped numatune
 c.add_invalid("--clock foo_tickpolicy=merge")  # Unknown timer
 
 
@@ -951,7 +951,7 @@ _cmdlist += vconv.cmds
 
 for _cmd in _cmdlist:
     newidx += 1
-    setattr(CLITests, "testCLI%s%d" % (_cmd.app.replace("-", ""), newidx),
+    setattr(CLITests, "testCLI%s%.4d" % (_cmd.app.replace("-", ""), newidx),
             maketest(_cmd))
 
 atexit.register(cleanup)