fix: Improve account and profile name validation

[obany]

Description of change

Improves the robustness of account and profile name validation.
Also fixes the getInitials when there were runs of whitespace in the name.

Links to any relevant issues

Fixes #296 #649 #719

Type of change

• Bug fix (a non-breaking change which fixes an issue)

How the change has been tested

Tested on windows with lots of different account names with odd characters, emojis, whitespace etc

Change checklist

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes