Fix JWT claim validation

[johakoch]

Currently (v1.12.1), there are (at least) two flaws in the JWT claim validation.

1. in validateClaims():

		if val != v {

This panics if the two variables have the same type and the type is uncomparable ([]interface{} or map[string]interface{}).

2. in getConfiguredClaims()

	claims = seetie.ValueToMap(val)

ValueToMap() creates a string slice for all list/tuple claim values by calling ValueToStringSlice(), regardless of the original type. So e.g.

claims = {
  a = [0, 1, 2]
}

will create []string{"0", "1", "2"}. This may be useful for some uses of seetie.ValueToMap(), but here is doesn't work properly.

[johakoch]

Apart from the JWT required claims, seetie.ValueToMap() is currently used for the following:

in eval/http.go: attributes values

• set_query_params
• add_query_params
• set_form_params
• add_form_params
• set_request_headers
• add_request_headers
• set_response_headers
• add_response_headers

in eval/lib/jwt.go: jwt signing config attribute values

• headers
• claims

in config/configload/helper.go: jwt signing config attribute values

• headers

in oauth2/client.go: jwt signing config attribute values

• headers
• claims

in handler/transport/oauth2_req_auth.go: jwt signing config attribute values

• headers
• claims

I guess that calling ValueToStringSlice() is potentially harmful in all cases apart from those in eval/http.go, where it could be argued to be a sort of user-friendly sanitization for non-string input.