Provide more placeholders for test params and test setup/teardown batch files

[csoltenborn]

Currently, we are providing the following placeholders for use in the Additional test execution params, test setup batch, and test teardown batch options: Test directory, thread id, and solution dir. Provide more placeholders, e.g.

• current test executable
• project dir

[csoltenborn]

Project dir is difficult to access - let's see if somebody needs it...