fix: use raw asn1js int value to improve performance

[achingbrain]

When converting an asn1js Integer to a base64url encoded string, use the raw byte value instead of converting it to a string, then a bigint, then bytes.

This greatly improves performance with a large peer store, and RSA peers in general, particularly during startup.

Before:

After:

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works

[SgtPooki]

Wow good find