Add tcpproxy

tcpproxy is a subset of github.com/inetaf/tcpproxy with some
modifications:
1- Implement the method SetRoutes to allow to set routes in bulk. Also
allows deletion of routes which otherwise would be impossible.
2- Implement round robin load balancing (there was no load balancing at
all).
3- Remove unused code.
4- Append Mirantis copyright for the modifications.

Additionaly this PR had to do some modifications in the copyright
linter script and `.golangci.yaml` because this is a file copied and
modified. This is required to Apache 2.0 retribution right.

Signed-off-by: Juan-Luis de Sousa-Valadas Castaño <[email protected]>

.golangci.yml

@@ -109,3 +109,9 @@ issues:
     - linters:
         - staticcheck
       text: "^SA1019:"
+
+    # tcpproxy is copied from https://github.com/inetaf/tcpproxy/, as per
+    # Apache 2.0 license section 4 (Redistribution) we must keep the original header.
+    - path: "pkg/component/controller/cplb/tcpproxy/.*"
+      linters:
+        - goheader

hack/copyright.sh

@@ -45,6 +45,10 @@ has_date_copyright(){
 # Copyright notice aren't related to the date of the document.
 for i in $(find cmd hack internal inttest pkg static -type f -name '*.go' -not -name 'zz_generated*'); do
     case "$i" in
+    pkg/component/controller/cplb/tcpproxy/*)
+    # These files have a special copyright due to being copied
+    # from github.com/inetaf/tcpproxy
+    ;;
     pkg/client/clientset/*)
         if ! has_basic_copyright "$i"; then
           echo "ERROR: $i doesn't have a proper copyright notice" 1>&2