Metadata: display_name syntax for algorithm title

[rldhont]

Defined a new metadata line to set the algorithm title without changes the algorithm id.

[JanCaha]

Nice 👍 This should be quite useful.

Would you mind adding a new test, so that this functionality can be properly checked? Should be as simple as adding new function into test_algorithm.py (there are plenty examples there) and you can add new testing script into qgis-processing-r/processing_r/test/data/.

[rldhont]

Thanks @Gustry

@JanCaha I have added tests. Ready for review

[JanCaha]

Great, thank you!