Prompt variables (#3359)

* wip prompt variables

* refactor backend + add popup suggestions menu to frontend

* use processString to replace all variables in system prompts

* update translations

* fix translations

* wip highlight variables

* revert accidental name change

* rename everything, remove translations

* Update prompt var UI and backend logic

* Update form handler
linting

* linting

* normalize all translation files for prompt variables

* prompt vars dev image

---------

Co-authored-by: Timothy Carambat <rambat1010@gmail.com>

.github/workflows/dev-build.yaml

@@ -6,7 +6,7 @@ concurrency:
 
 on:
   push:
-    branches: ['chore-bump-lancedb'] # put your current branch to create a build. Core team only.
+    branches: ['3157-feat-prompt-variables'] # put your current branch to create a build. Core team only.
     paths-ignore:
       - '**.md'
       - 'cloud-deployments/*'