feat: Add utility for logging sensitive information using encryption (#29682)

Introduces `common.djangoapps.util.log_sensitive module` for
public-key encryption of sensitive debug information in log
messages, including CLI commands for generating keys and
decrypting log output.

Also:

- Adds `PyNaCl` to base requirements for encryption tools
- Requirements upgrade

ref: ARCHBOM-1940

scripts/xblock/requirements.txt

@@ -6,7 +6,7 @@
 #
 certifi==2021.10.8
     # via requests
-charset-normalizer==2.0.9
+charset-normalizer==2.0.10
     # via requests
 idna==3.3
     # via requests