Add golang-1.26-linux BOSH package and declare it as health_monitor dependency

Copies the vendored golang-1.26-linux package (from cloudfoundry/bosh-package-golang-release)
which was already present on experiment-golang-bosh-nats-sync. Without this package
packages/health_monitor/spec had no golang dependency, so BOSH would not guarantee
the Go toolchain was compiled before health_monitor during a release build.

The packages/health_monitor/packaging script already loops for golang-* packages;
the spec declaration ensures the compilation ordering is explicit.

ai-assisted=yes
[TNZ-113909] Convert BOSH health monitor job to Golang

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/health_monitor/spec

@@ -1,5 +1,8 @@
 ---
 name: health_monitor
 
+dependencies:
+- golang-1.26-linux
+
 files:
 - bosh-monitor/**/*

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

@@ -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/runtime.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}"