Reimplement kubectl plugin release workflow (#8812)

* Feat: reimplement kubectl plugin release system

This commit does the following changes:
- Add GitHub Actions pipeline for releasing the plugin
- Removes the build/build-plugin.sh and replaces this with GoReleaser
- Adds the use of krew-release-bot for automatically updating the krew
  release
- Removes the make target for build/build-plugin.sh

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

* Fix: pin github actions stages with commit sha

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

build/build-plugin.sh

@@ -1,84 +0,0 @@
-#!/bin/bash
-
-# Copyright 2018 The Kubernetes Authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-if [ -n "$DEBUG" ]; then
-	set -x
-fi
-
-set -o errexit
-set -o nounset
-set -o pipefail
-
-declare -a mandatory
-mandatory=(
-  PKG
-  ARCH
-  COMMIT_SHA
-  REPO_INFO
-  TAG
-)
-
-missing=false
-for var in "${mandatory[@]}"; do
-  if [[ -z "${!var:-}" ]]; then
-    echo "Environment variable $var must be set"
-    missing=true
-  fi
-done
-
-if [ "$missing" = true ]; then
-  exit 1
-fi
-
-export CGO_ENABLED=0
-
-release=cmd/plugin/release
-
-function build_for_arch(){
-  os=$1
-  arch=$2
-  extension=$3
-
-  echo "> building targets for ${os}-${arch}"
-
-  env GOOS="${os}" GOARCH="${arch}" go build \
-    ${GOBUILD_FLAGS} \
-    -trimpath -ldflags="-buildid= -w -s \
-      -X ${PKG}/version.RELEASE=${TAG} \
-      -X ${PKG}/version.COMMIT=${COMMIT_SHA} \
-      -X ${PKG}/version.REPO=${REPO_INFO}" \
-    -o "${release}/kubectl-ingress_nginx${extension}" "${PKG}/cmd/plugin"
-
-    cp LICENSE ${release}
-    tar -C "${release}" -zcvf "${release}/kubectl-ingress_nginx-${os}-${arch}.tar.gz" "kubectl-ingress_nginx${extension}" LICENSE
-    rm "${release}/kubectl-ingress_nginx${extension}"
-    hash=$(sha256sum "${release}/kubectl-ingress_nginx-${os}-${arch}.tar.gz" | awk '{ print $1 }')
-    sed -i "s/%%%shasum_${os}_${arch}%%%/${hash}/g" "${release}/ingress-nginx.yaml"
-}
-
-rm -rf "${release}"
-mkdir "${release}"
-
-cp cmd/plugin/ingress-nginx.yaml.tmpl "${release}/ingress-nginx.yaml"
-
-sed -i "s/%%%tag%%%/${TAG}/g" ${release}/ingress-nginx.yaml
-
-echo "Generated targets in ${release} directory."
-
-build_for_arch darwin amd64 ''
-build_for_arch darwin arm64 ''
-build_for_arch linux amd64 ''
-build_for_arch windows amd64 '.exe'