Chore: Detaching go tools from the main Grafana workspace (#104861)

* add script for tooling

* add to make

* not to forget

* reworked go tools

* add tool installation script

* adding readme

* updating readme

* updating readme

* cleanup install.sh and makefile

* update the readme file

* cleanup scripts

* switch variables.mk to lazy evaluation

* add tools ache to gitignore

* get rid of absolute path in hte Variables.mk file

* switch to reusable function for path generation

* add debug statements

* add create cache tool dir

* add debuig statements to make file

* drop tool cache

* fix race condition n ci

* fix race condition n ci

* cleanup workspace

* add lefthook.rc to codeowners

* copy .citools folder to docker image

* switch back to main branch of grafana-build

* Add .citools to the drone builder

* fix wording in generate.sh and README.md

.citools/generate.sh

@@ -0,0 +1,36 @@
+#!/bin/bash
+set -euo pipefail
+
+TOOLS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+TOOLS_SRC_DIR="$TOOLS_DIR/src"
+TOOLS_MK="$TOOLS_DIR/Variables.mk"
+
+echo "# Generated tool paths" > "$TOOLS_MK"
+
+cat <<'EOL' >> "$TOOLS_MK"
+tools_dir := $(shell cd $(dir $(lastword $(MAKEFILE_LIST))) && pwd)
+src_dir := $(tools_dir)/src
+
+# Due to a race condition, after initial call to `go tool` golang may report a wrong binary location pointing to the invalid `/tmp/go-buildXXX` directory
+define compile_tool
+$(shell \
+  (cd $(src_dir)/$(1) \
+  && GOWORK=off go tool -n $(2) > /dev/null \
+  && GOWORK=off go tool -n $(2)) | sed 's/^[[:space:]]*//g'; \
+)
+endef
+
+EOL
+
+for tooldir in "$TOOLS_SRC_DIR"/*; do
+  [ -d "$tooldir" ] || continue
+  tool=$(basename "$tooldir")
+  fqtn=$(awk '/^tool / { print $2 }' "$tooldir/go.mod")
+
+  cat <<EOL >> "$TOOLS_MK"
+
+# Tool: "$tool"
+${tool} = "\$(call compile_tool,${tool},${fqtn})"
+EOL
+done