http - align OTEL http attributes with latest standard #409

to maintain compatibility with external tooling we should make sure our attribute respect the latest (stable) semantic conventions. When we initially implemented things, the spec was still in draft. The following attributes need to be renamed in the middleware handlers and in the request adapter:
htttp.status_code => http.response.status_code
http.response_content_length => http.response.body.size
http.request_content_length => http.request.body.size
http.flavor => network.protocol.name
http.response_content_type => http.response.header.content-type
http.request_content_type => http.request.header.content-type
http.method => http.request.method
http.host => url.scheme
http.scheme => server.address
http.uri => url.full
http.uri_template => url.uri_template

link to the spec for more information https://opentelemetry.io/docs/specs/semconv/attributes-registry/http/
related microsoftgraph/msgraph-sdk-design#108