Fix bosh create-release to work for integration tests

- Replace golang-1.26-linux spec.lock (vendored, no GCS blob yet) with
  a proper spec+packaging that can be built from source. The CI pipeline's
  bump-golang-package job will convert this back to the vendor-package
  approach once the blob is uploaded to GCS.
- Fix packages/nats/spec: BOSH prepends src/ automatically, so the file
  pattern should be bosh-nats-sync/**/* not src/bosh-nats-sync/**/*
- Fix packages/nats/packaging: BOSH strips src/ when extracting package
  files, so the compile target is bosh-nats-sync/ not src/bosh-nats-sync/
- Add src/golang-1.26-linux/compile.env.unix and runtime.env.unix from
  bosh-package-golang-release for the packaging script

Author: aramprice

packages/golang-1.26-linux/packaging

@@ -0,0 +1,7 @@
+set -e -x -u
+
+mkdir "${BOSH_INSTALL_TARGET}/bosh"
+
+PACKAGE_NAME="$(basename "${BOSH_INSTALL_TARGET}")"
+sed "s#\${PACKAGE_NAME}#${PACKAGE_NAME}#" golang-1.26-linux/compile.env.unix > "${BOSH_INSTALL_TARGET}/bosh/compile.env"
+sed "s#\${PACKAGE_NAME}#${PACKAGE_NAME}#" golang-1.26-linux/runtime.env.unix > "${BOSH_INSTALL_TARGET}/bosh/runtime.env"

packages/golang-1.26-linux/spec

@@ -0,0 +1,8 @@
+---
+name: golang-1.26-linux
+
+dependencies: []
+
+files:
+- golang-1.26-linux/compile.env.unix
+- golang-1.26-linux/runtime.env.unix

packages/golang-1.26-linux/spec.lock

@@ -10,5 +10,5 @@ source /var/vcap/packages/golang-1.26-linux/bosh/compile.env
 unset GOPATH
 export GO111MODULE=on
 
-cd src/bosh-nats-sync
+cd bosh-nats-sync
 CGO_ENABLED=0 go build -mod=vendor -o "${BOSH_INSTALL_TARGET}/bin/bosh-nats-sync" ./cmd/bosh-nats-sync

packages/nats/packaging

@@ -6,4 +6,4 @@ dependencies:
 
 files:
 - nats/nats-server-v*-linux-amd64.tar.gz
-- src/bosh-nats-sync/**/*
+- bosh-nats-sync/**/*

packages/nats/spec

@@ -0,0 +1,10 @@
+if [ -z "${BOSH_PACKAGES_DIR:-}" ]; then
+ export GOROOT=$(readlink -nf /var/vcap/packages/${PACKAGE_NAME})
+else
+ export GOROOT=$BOSH_PACKAGES_DIR/${PACKAGE_NAME}
+fi
+
+export GOPATH=$PWD
+export GOCACHE=/var/vcap/data/${PACKAGE_NAME}/cache
+export GOTOOLCHAIN=local
+export PATH=$GOROOT/bin:$GOPATH/bin:$PATH

src/golang-1.26-linux/compile.env.unix

@@ -0,0 +1,4 @@
+export GOROOT=$(readlink -nf /var/vcap/packages/${PACKAGE_NAME})
+export GOCACHE=/var/vcap/data/${PACKAGE_NAME}/cache
+export GOPATH="${PWD}"
+export PATH="${GOROOT}/bin:${GOPATH}/bin:${PATH}"