[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

.gitignore

@@ -40,6 +40,7 @@ __debug_bin*
 # This is the new place of the block, but I leave the previous here for a while
 /devenv/docker/blocks/auth/saml-enterprise
 /devenv/docker/blocks/auth/signer
+/devenv/docker/blocks/spanner_tests
 
 /tmp
 tools/phantomjs/phantomjs
@@ -103,14 +104,18 @@ profile.cov
 /pkg/cmd/grafana-cli/grafana-cli
 /pkg/cmd/grafana-server/grafana-server
 /pkg/cmd/grafana-server/debug
-/pkg/extensions/*
-/pkg/build/cmd/artifactspage.go
-/pkg/build/cmd/artifactspage.tmpl.html
-/pkg/build/cmd/exportversion.go
-/pkg/server/wireexts_enterprise.go
+
+# Extensions
 /pkg/cmd/grafana-cli/runner/wireexts_enterprise.go
+/pkg/server/wireexts_enterprise.go
+/pkg/build/cmd/enterprise.go
+/pkg/extensions/*
+!/pkg/extensions/.keep
 !/pkg/extensions/main.go
 /public/app/extensions
+!/public/app/extensions/.keep
+
+
 debug.test
 /examples/*/dist
 /packaging/**/*.rpm
@@ -170,6 +175,7 @@ compilation-stats.json
 /e2e/benchmarks/**/results
 /e2e/build_results.zip
 /e2e/extensions
+!/e2e/extensions/.keep
 /e2e/extensions-suite
 /test-results/
 /playwright-report/