Switches the Math.random in password_gen.js to a more cryptographically secure method.

[LaserBread]

Description

Resolves a security vulnerability CodeQL found in our core/lib/password_gen.js file by using the crypto library instead of the less cryptographically secure Math.random.

Fixes a connected CodeQL vulnerability

Checklist:

Before you submit your Pull Request, please make sure you have completed the following tasks:

• 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.
• My changes generate no new warnings.
• 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.
• Any dependent changes have been merged and published in downstream modules.
• I have tagged my PR with the appropriate label(s).

[MigrainePanda]

Can you add that it fixes security alert #19 (Insecure randomness)?

[LaserBread]

It is linked in the issue on the security tab.