Enhance external calls inference logic

[srikanthccv]

It should consider rpc calls. It should look at the url parts (http.host, host.port, http.scheme) if the attribute http.url doesn't exist. There are not so widely used things such as Faas which still fall under the category.

• include rpc calls and check it full url can be constructed from parts #1305
• FasS

[srikanthccv]

This is done. The FAAS should be included as well. I will close this one for this sprint. Although we tried to cover mostly everything, If there are edge cases missing we will gather more information about them and address them in future.