Display computed rules list

[dchenk]

Feature request

Is your feature request that we implement a new rule?
No.

Is your feature request related to a problem? Please describe.
It's often difficult to determine which rules are active and in what configuration. I'm often needing to search through the list of rule sets listed in extends to figure out what's being overridden where.

Describe the solution you'd like
There should be a CLI command that will display the list of computed rules. The command could be named something like --display-computed. If the option is present when tslint is invoked, you would simply get a print out in standard output of a JSON array of the resultant rules after combining all the imported and overridden rules.

Describe alternatives you've considered
There doesn't appear to be a way to get tslint to display precisely how it resolved all the rules given to it.

Additional context
ClangFormat has such a feature (named -dump-config): https://clang.llvm.org/docs/ClangFormat.html

[adidahiya]

Yeah, this would be nice to have. Related: #2267, #4608, #3828

[JoshuaKGoldberg]

I believe this particular issue is duplicate of #3720, which was resolved in #4744. Please do post here if that's not the case!