[FEATURE] Add encode/decode to PPL

[A-Gray-Cat]

Is your feature request related to a problem?
When analyzing website access logs, encoded URL path needs to be decoded to help analysts conveniently see the query string. Analysts would also do Base64 encoding and decoding.

What solution would you like?
An encode, and decode function that can take in a string, and the encoding scheme defined by the user, and the encode and decode function would encode and decode the string using the specified scheme.

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.

[YANG-DB]

@A-Gray-Cat this can actually be covered using the existing ppl parse command with the build-in patterns shown here
please let me know if this covers the requirements