Enrich support for HttpClientMetrics

[alexarchen]

The best way to add urls into HttpClientMetrics is to use Enrich possibility so that subscriber can select meaningful part of request by himself.
Alternative way is to use the list of possible endpoints that url can match => tag is the name of endpoint.
Filter is also desirable

[aunikitin]

Hello, I made MR. Does it the same?

[martinjt]

High-Cardinality data such as URL shouldn't go into metrics.

That said, enrichment support was something to look at once the stable releases were out. @CodeBlanch is now the time to look at this?