Add gosec linter (#1342)

This PR adds `gosec` linter with the following checks disabled:

- G102: Bind to all interfaces
- G107: Url provided to HTTP request as taint input
- G112: Potential slowloris attack
- G114: Use of net/http serve function that has no support for setting timeouts
- G204: Audit use of command execution
- G401: Detect the usage of DES, RC4, MD5 or SHA1
- G402: Look for bad TLS connection settings
- G404: Insecure random number source (rand)
- G501: Import blocklist: crypto/md5
- G505: Import blocklist: crypto/sha1

We have complaints related to the checks above. They have to be addressed separately.

client/firewall/uspfilter/uspfilter.go

@@ -355,14 +355,16 @@ func (m *Manager) RemovePacketHook(hookID string) error {
 	for _, arr := range m.incomingRules {
 		for _, r := range arr {
 			if r.id == hookID {
-				return m.DeleteRule(&r)
+				rule := r
+				return m.DeleteRule(&rule)
 			}
 		}
 	}
 	for _, arr := range m.outgoingRules {
 		for _, r := range arr {
 			if r.id == hookID {
-				return m.DeleteRule(&r)
+				rule := r
+				return m.DeleteRule(&rule)
 			}
 		}
 	}