PR: Follow-up to removing CONF from mouse_shortcuts (Editor)

[athompson673]

Description of Changes

PR: Remove CONF usage in MouseShortcutEditor (Editor)
#24250 (comment)

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

Refactor setting mouse shortcuts CONF to use SpyderConfigurationAccessor api

Issue(s) Resolved

Fixes #

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: athompson673

[ccordoba12]

Thanks @athompson673!