Add ability to provide custom normalization of URI mapping saved as resource name

[marcindabrowski]

In PHP client there is possibility to configure the mapping of resource name: Map resource names to normalized URI.

Please introduce something like this in Java library.
Now tags with resource names are somehow obfuscated, but it is not working perfectly - I have similar issue as in DataDog/dd-trace-php#455.

It also would be nice to have host in some tag or in resource name. Why? We are connecting to services provided by different companies, and they have the same path, ie.: path to OAuth2 token. Now it is impossible to distinguish metrics for those calls.