Added [ParamsAllValues]

[svick]

Closes #658.

The name is ParamsAllValues, because it can get all values not just for enum, but also for other types with tiny number of values (see the documentation).

[AndreyAkinshin]

Hey, @svick, thanks for the PR!

Could you replace integration tests with regular unit tests?
Our integration tests take too much time, we use it only in cases when we want to check that we can build and run a benchmark against specific toolchains.
In you case, you just want to check that ParamsAllValues was parsed correctly. You don't have to actually run a benchmark for this.

I guess that the best way to test this feature is approval tests (see MarkdownExporterApprovalTests as an example). It's still not a perfect solution, but it's the simplest one for now (and we can run such tests almost instantly.

[AndreyAkinshin]

I think that we also should implement a validator (e.g., see BaselineValidator) instead of throwing InvalidOperationException. This approach allows printing a nice user-friendly message which describes the problem. All validation errors can be collected via special API (without try-catch blocks) and it doesn't break all execution process for all benchmarks, it just disables a benchmark with invalid config.

[AndreyAkinshin]

Incomplete

[AndreyAkinshin]

@svick, I close this PR since we don't have any updates since February. Feel free to open another one in case if you resolve the review comments.