implemented horizontal resize

[rozyczko]

Description

Molecular formulas can be long. The current design of the density calculator hinders longer formulas visibility. This PR fixes the issue by allowing the calculator to be horizontally resizable.

Fixes #3804

How Has This Been Tested?

Local win11

Review Checklist:

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Documentation (check at least one)

• There is nothing that needs documenting
• Documentation changes are in this PR
• There is an issue open for the documentation (link?)

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)