Flag redundant settings

Currently, it is not obvious to a user, if a setting is already inherited from the default configuration and thus can be omitted.

Example:

orgs.newBranchProtectionRule('main') {
  allows_deletions: false
},

if allows_deletions is already defined like that in the default config, specifying it again is redundant.

Ideally we should flag redundant settings during validation. However, this is not trivial, as otterdog processes the resulting json which has no resemblance anymore with the original config.

A solution could be to export the json again to jsonnet and diff it with the original config which should outline unnecessary settings.