Reorganised Script Generator buttons to fix scaling issue

[Spencer-Cheverton]

Description of work

Reorganised script generator buttons so they take up less space, and ensured they don't resize when the window is resized.

Ticket

ISISComputingGroup/IBEX#8826

Acceptance criteria

• Varying screen height in the script generator view of the GUI does not shrink the buttons

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Code Review

• Is the code of an acceptable quality?
• If the change is to an OPI, does the check_opi_format.py script in C:\Instrument\Dev\ibex_gui\base\uk.ac.stfc.isis.ibex.opis pass?
• Do the changes function as described and is it robust?
• Is there associated PR for the release notes?

Final Steps

• Reviewer has also merged the release notes