Support for subsetting CEL standard library and serialization of CEL environments to YAML.

CEL is an official Google product [#1122]

Features

• Helper methods for subsetting function overloads [#1120]
• Introduce cel package aliases for Activation [#1123]
• Canonical environment description and stdlib subsetting [#1125]
• Support for cel.Env conversion to YAML-serializable config [#1128]
• Option to configure CEL via env.Config object [#1129]
• Support for feature flags and validators in env.Config [#1132]
• Add k8s custom policy tag handler for test [#1121]

Fixes

• ContextEval support for Unknowns [#1126]
• Fix godoc formatting for Lists and OptionalTypes functions [#1127]
• Default enable DefaultUTCTimeZone [#1130]
• Support for splitting nested branching operators within policies [#1136]

New Contributors

• @chaewonkong made their first contribution in #1127

Full Changelog: v0.23.2...v0.24.0