EngDiff UI tries to save files to invalid paths if punctuation in RB Number box

[RichardWaiteSTFC]

Describe the bug Punctuation such as (\ : - /) in RB Number box in the EngDiff UI results in the save directory being truncated and the interface tries to write files (from calibration and focus tabs) into directories which do not exist.

To Reproduce (1) Follow Test 2 in the manual testing instructions (latest version not yet merged) - using punctuation e.g. My_RB-Num\ber https://github.com/mantidproject/mantid/blob/33e61abf3a7ed9a3e352ca91886efe03d9afc5b8/dev-docs/source/Testing/EngineeringDiffraction/EngineeringDiffractionTestGuide.rst

Expected behavior Overwrites RB number entered with truncated string - or doesn't accept punctuation?

Screenshots

Platform/Version (please complete the following information):

• OS: [e.g. Windows, RHEL 7, Ubuntu, macOS]
• OS Version:
• Mantid Version [e.g. 6.0.0]

Additional context

[RichardWaiteSTFC]

Found in manual testing #34353