Compile expr in config

[antonmedv]

Summary

Looks like expr is used mostly via expr.Eval. While it is a valid usage, precompiling expressions on config save/update can detect a lot of errors.

Consider using expr.Compile. One of the expr features is type checker:

out, err := expr.Compile(`name + age`)
// err: invalid operation + (mismatched types string and int)
// | name + age
// | .....^

Type checker can infer types from Argo env variables, so there is no need to redefine types for expr.

Use Cases

Detecting errors in expression of configuration save/update.

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[agilgur5]

This would be a great validation step to add to the operator and CLI, thanks for the suggestion!

Related to the goals of #10017 as well