utils/httpexpect: add httptrace.ClientTrace

[mmatczuk]

This allows to inspect the HTTP client events in the test client. It's not enabled by default.

Example:

=== RUN   TestProxyGoogleCom
    trace.go:19: GetConn for hostPort: proxy:3128
    trace.go:38: DNSStart: {Host:proxy}
    trace.go:41: DNSDone: {Addrs:[{IP:172.23.0.3 Zone:}] Err:<nil> Coalesced:false}
    trace.go:44: ConnectStart: network=tcp, addr=172.23.0.3:3128
    trace.go:47: ConnectDone: network=tcp, addr=172.23.0.3:3128, err=<nil>
    trace.go:50: TLSHandshakeStart
    trace.go:56: TLSHandshakeDone: state={Version:772 HandshakeComplete:true DidResume:false CipherSuite:4865 NegotiatedProtocol:http/1.1 NegotiatedProtocolIsMutual:true ServerName:www.google.com PeerCertificates:[0x40002f2680 0x40002f2c00] VerifiedChains:[[0x40002f2680 0x40002f3180]] SignedCertificateTimestamps:[] OCSPResponse:[] TLSUnique:[] ekm:0x1eb060}
    trace.go:22: GotConn: {Conn:0x4000092a80 Reused:false WasIdle:false IdleTime:0s}
    trace.go:60: WroteHeaderField: key=Host, value=[www.google.com]
    trace.go:60: WroteHeaderField: key=User-Agent, value=[Go-http-client/1.1]
    trace.go:63: WroteHeaders
    trace.go:69: WroteRequest: {Err:<nil>}
    trace.go:28: GotFirstResponseByte
    trace.go:25: PutIdleConn with error: <nil>

[what-the-diff]

PR Summary

• Introduction of HTTP Request Tracing
  Our team added a new functionality to the Client structure which allows for detailed tracking of the HTTP requests. This will facilitate better monitoring and debugging for all HTTP requests carried out within the app.

• Addition of Test Client Trace Implementation
  A new file trace.go was added to our project. It contains code for a new testing trace client designed to emulate and simulate real-life scenarios, improving the accuracy and reliability of our testing process.