add gosimport to make fmt and run it (#25383)

* add gosimport to make fmt and run it

* move installation to tools.sh

* correct weird spacing issue

* Update Makefile

Co-authored-by: Nick Cabatoff <ncabatoff@hashicorp.com>

* fix a weird issue

---------

Co-authored-by: Nick Cabatoff <ncabatoff@hashicorp.com>

tools/tools.sh

@@ -46,6 +46,7 @@ install_external() {
     gotest.tools/gotestsum@latest
     honnef.co/go/tools/cmd/staticcheck@latest
     mvdan.cc/gofumpt@latest
+    github.com/rinchsan/gosimports/cmd/gosimports@latest
   )
 
   echo "==> Installing external tools..."
@@ -72,6 +73,7 @@ check_external() {
     protoc-go-inject-tag
     revgrep
     staticcheck
+    gosimports
   )
 
   echo "==> Checking for external tools..."