Add compilation of tikz images to pull requests

[pvogt09]

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What does this PR aim to accomplish?:
Add ability to compile tikz pictures in pull requests.

How does this PR accomplish the above?:
Adds action step and script to compile tikz pictures.

What documentation changes (if any) are needed to support this PR?:
None.

[pvogt09]

Does not work correctly because:

• Job does not exit with failure when compilation of tikz pictures fails.
• Produced pdf files can not be found by convert.
• Job should only run for the changed images and not all.
• Metadata like creation dates should optionally be removes from the pictures to make them comparable.