Migrate usage of metrics.Handler to metricDefinition.With

[luansapelli]

What changed?

Using the new metricDefinition.With approach.

Why?

The usage of metrics.Handler could be both redundant and unsafe:

 handler.Histogram( myHisto.Name(), myHisto.Unit() ).Record(...)
                │             │               └───┐
                │             │                   │
                └─────┐       └───────────┐       │
                      │                   │       │
       Redundant and Unsafe: 'Histogram'  │       │
       is specified despite knowing       │       │
       'myHisto' is a histogram. There's  │       │
       also a risk if 'myHisto.Name()'    │       │
       refers to a metric definition that │       │
       is not a histogram.                │       │
                                          └─── Redundant information

And using the new With(Handler) method, there's no need to specify redundant information.

How did you test it?

Already exists an ExampleHandler which tests all the new approach methods.

Potential risks

People can still use the old approach, because we are keeping the Handler interface as-is.

Is hotfix candidate?

No.