[Enterprise] Consolidate extensions folders and keep them around (#98486)

* WIP: copy approach

* Fix package name

* Do not ignore .keep for frontend extensions

* Add keep file for frontend extensions

* Tweak makefile to generate enterprise swagger or not

* Remove duplicate imports

* Add build extensions

* Add CMD extensions

* Add keep to e2e extensions

* Add .keep

* Reduce file structure changes

* Ignore boring crypto

* Add e2e extensions keep file

* Remove enterprise file

* Update .gitignore

* Move things around

* Update git ignore

* Consolidate backend extensions folder

* Move enterprise deps

* Update comment

* Do not use build tags

* Ignore setting enterprise

* Revert changes in makefile

* Revert package changes

* Add back extensions main.go

* Update git ignore

* Ignore spanner tests

* Trick ignore files only by git

* Add .ignore file to CODEOWNERS for frontend-ops

* Fix issue with noisy duplicate targets

.github/CODEOWNERS

@@ -444,6 +444,7 @@
 /.betterer.eslint.config.js @grafana/frontend-ops
 /.gitattributes @grafana/frontend-ops
 /.gitignore @grafana/frontend-ops
+/.ignore @grafana/frontend-ops
 /.nvmrc @grafana/frontend-ops
 /.prettierignore @grafana/frontend-ops
 /.yarn @grafana/frontend-ops