Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/ui/user_remove.go

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package ui // import "miniflux.app/v2/internal/ui"
+
+import (
+	"errors"
+	"net/http"
+
+	"miniflux.app/v2/internal/http/request"
+	"miniflux.app/v2/internal/http/response/html"
+	"miniflux.app/v2/internal/http/route"
+)
+
+func (h *handler) removeUser(w http.ResponseWriter, r *http.Request) {
+	loggedUser, err := h.store.UserByID(request.UserID(r))
+	if err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	if !loggedUser.IsAdmin {
+		html.Forbidden(w, r)
+		return
+	}
+
+	selectedUserID := request.RouteInt64Param(r, "userID")
+	selectedUser, err := h.store.UserByID(selectedUserID)
+	if err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	if selectedUser == nil {
+		html.NotFound(w, r)
+		return
+	}
+
+	if selectedUser.ID == loggedUser.ID {
+		html.BadRequest(w, r, errors.New("You cannot remove yourself"))
+		return
+	}
+
+	if err := h.store.RemoveUser(selectedUser.ID); err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	html.Redirect(w, r, route.Path(h.router, "users"))
+}