ONETEP interface: performance and various bug fixes

Checklist

• I have read the contribution guidelines.
• Unit tests have been added for any new or changed code, and the test suite passes. Note: Your request will likely not be merged without the appropriate tests.
• "closes #XXXX" is in the body of the MR description to link the related issue, if applicable.

An updated version of the ONETEP interface

• Regex is used to make the search more robust (thanks to errors pointed by @ndmhine)
• There is a presearch using regex "|" that speed up file search by ~ 20
• 'Onetep species' are retrieved only when necessary and if integers are used, tags are used instead.
• Various bug fixes when reading geometry optimisation (some geometries were missing)
• Fixed a bug when the reader would fail if used on a unique atom calculation.
• Cell is correctly retrieved.
• Stress case removed for now.
• Full Backward compatibility with the old 'ASE_ONETEP_COMMAND' for now.

Tests are passing