Support full suite of cel-go extensions

[salrashid123]

Feature Description

Support cel-go extensions and document the set of extensions supported.

• https://github.com/google/cel-go/tree/master/ext

Better yet, allow an option box in the playground that enables/disables extensions (atleast cel-go extensions)

eg right now only the "strings" is supported

https://github.com/undistro/cel-playground/blob/main/eval/eval.go#L31

so this works now but not the stuff like base64.*

jwt.iss.lowerAscii() == 'auth.acme.com:12350'

[matheusfm]

Hi @salrashid123
Thank you for the suggestion!
Your idea makes a lot of sense, and we appreciate your contribution to the project.
We'll definitely consider implementing it. Any PR is welcome here!