This commit updates the remaining tests cases for LAVA
integration.

The change consists in adding the `git-repos` directive so they
can fetch the tests scripts from LAVA.

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

- Update the README listing existing macros and how to
  use the renderer.
- Rename the main program to render-test-case
- Rename the tc directory to tests-cases

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

This commit addes a parser for the test case format, so it can
detect the most common mistakes (missing field or incorrect types
for values) in the test case yaml file.

This commit also adds a few more ported test cases.

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>