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/ui/client_ui.go

@@ -634,5 +634,5 @@ func checkPIDFile() error {
 		}
 	}
 
-	return os.WriteFile(pidFile, []byte(fmt.Sprintf("%d", os.Getpid())), 0o664)
+	return os.WriteFile(pidFile, []byte(fmt.Sprintf("%d", os.Getpid())), 0o664) //nolint:gosec
 }