Precompile fomantic-ui files (#13332)

We rarely change fomantic-ui or its configuration so it's kind of a
waste to have it rebuild on every CI run. These changes remove the
fomantic files from the build and instead add the relevant output files
to the git index, which should shave of 2-3 minutes on every CI run.

`make fomantic` should still work and should be ran whenever fomantic is
updated or its configuration is changed.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Makefile

@@ -210,7 +210,7 @@ node-check:
 
 .PHONY: clean-all
 clean-all: clean
-	rm -rf $(WEBPACK_DEST_ENTRIES) $(FOMANTIC_DEST_DIR)
+	rm -rf $(WEBPACK_DEST_ENTRIES)
 
 .PHONY: clean
 clean:
@@ -323,7 +323,7 @@ watch:
 	bash tools/watch.sh
 
 .PHONY: watch-frontend
-watch-frontend: node-check $(FOMANTIC_DEST) node_modules
+watch-frontend: node-check node_modules
 	rm -rf $(WEBPACK_DEST_ENTRIES)
 	NODE_ENV=development npx webpack --hide-modules --display-entrypoints=false --watch --progress
 
@@ -541,7 +541,7 @@ install: $(wildcard *.go)
 build: frontend backend
 
 .PHONY: frontend
-frontend: node-check $(FOMANTIC_DEST) $(WEBPACK_DEST)
+frontend: node-check $(WEBPACK_DEST)
 
 .PHONY: backend
 backend: go-check generate $(EXECUTABLE)