build: update devcontainer and use latest codespaces features (#36422)

* build: update devcontainer to latest build image

* build: add update-content-command

* build: set good vscode config

* build: be less noisy in update command

* build: only run sync in prebuild environment

* build: list env vars

* build: run sync always

.devcontainer/on-create-command.sh

@@ -10,6 +10,7 @@ export PATH="$PATH:$buildtools/src"
 
 # Create the persisted buildtools config folder
 mkdir -p $buildtools_configs
+mkdir -p $gclient_root/.git-cache
 rm -f $buildtools/configs
 ln -s $buildtools_configs $buildtools/configs