Log Rule Id on malformed configuration error

[hefekranz]

Is your feature request related to a problem? Please describe.

When having a big pile of rules and a single config error among them, it's pretty hard to figure out which one it is.

Describe the solution you'd like

I'd like to see the Id of the rule with the error in the logs.

oathkeeper/rule/repository_memory.go

Line 114 in a76f749

Errorf("A rule uses a malformed configuration and all URLs matching this rule will not work. You should resolve this issue now.")

Describe alternatives you've considered

I used a fork to figure out which rules were flawed.
Additional context

I can push a PR if you are ok with that.

[aeneasr]

Totally makes sense! PRs appreciated!