Add formatter script to sampler codebase

[RobinSattler]

I was talking with @AxelKrypton about adding a codebase formatter to the sampler repo. He proposed (since the sampler repo needs SMASH anyways to be installed) that a good solution would be to write a small formatter script which reuses SMASH’s codebase-format-helper.bash internally.

For tracking purposes a small transcript from our conversation and which steps he suggested:

1. Change SMASH script to call the Main function only when the script is executed and not sourced. If needed, move the out-of-function lines to a function and call it accordingly.
2. Create a new script in the sampler that is going to be the new tool.
3. In it test the SMASH_DIR environment variable to check it points to a valid existing location.
4. Use it to source the SMASH script. This will do nothing as only functions are sourced.
5. Redefine the look_for_files_to_format function (I think this the only needed change) tailoring it to the sampler codebase
6. Assemble a new Main function if needed or just call it.