[snipmatch] Bug 451218: Add ${:importStatic(...)} for methods

Previously, "Create Snippet" didn't generate ${:importStatic(...)}
variables for statically imported methods.

Also addresses Bug 451639 by restructuring of SnippetCodeBuilder and
its tests.

Change-Id: I598d75f4777b96629cc038536f746fc9b55ad887
Signed-off-by: Andreas Sewe <andreas.sewe@codetrails.com>
Signed-off-by: Simon Laffoy <simon.laffoy@codetrails.com>
Merge "[snipmatch] Bug 451218: Add ${:importStatic(...)} for methods"