feat: generate signing key

[oSumAtrIX]

Type

Functionality

Issue

Currently, the manager exposes its signing password in version control: https://github.com/revanced/revanced-manager/blob/e12532ea4c149bde6e78efe5d3e27283d3909f80/android/app/src/main/kotlin/app/revanced/manager/flutter/MainActivity.kt#L244

Feature

Auto-generate the password. Allow to change it in the settings.

Motivation

This way, the password would not be leaked, strong through a default random key and thus the keystore file would remain secure.

Additional context

No response

Acknowledgements

• [X] I have searched the existing issues and this is a new and no duplicate or related to another open issue.
• [X] I have written a short but informative title.
• [X] I filled out all of the requested information in this issue properly.
• [X] The issue is related solely to the ReVanced Manager