Use a more efficient Base64 Encoder/Decoder

[mdedetrich]

What is currently missing?

Currently we are using Java's basic java.util.Base64 encoder/decoder to transform the byte arrays into Base64, we should explore faster/more efficient options

The streaming here is also applicable since the payloads for kafka messages can potentially be quite large

How could this be improved?

There already appears to be a highly performant solution used by akka-http at https://github.com/akka/akka-http/blob/main/akka-parsing/src/main/java/akka/parboiled2/util/Base64.java

Note that akka-http is already available in guardian as a transitive dependency so no dependencies need to be added.

Is this a feature you would work on yourself?

• I plan to open a pull request for this feature