Add unit tests.

These test the complete workflow as the user experiences it when
clicking "Start".
Intended usage:
    (1) Run sdktool to set up a kit with the toolchain you want
        to test against (using a temporary directory).
        The tests assume exactly one Kit to be present.
    (2) Start Creator with a matching settings path and
        "-load ClangStaticAnalyzer -test ClangStaticAnalyzer".
    (3) Repeat until all toolchains have been tested.
The initial implementation tests one trivial source file
with both qbs and qmake.

Change-Id: I810f23e2990a789a4dd9f1dd16335fbcf5c5f39f
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

plugins/clangstaticanalyzer/unit-tests/simple/main.cpp

@@ -0,0 +1,5 @@
+int main()
+{
+    int *i = 0;
+    *i = 42;
+}