Rework addons (use rpc) (#3268)

Co-authored-by: Anbraten <6918444+anbraten@users.noreply.github.com>

server/forge/addon/plugin.go

@@ -0,0 +1,43 @@
+// Copyright 2024 Woodpecker Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package addon
+
+import (
+	"net/rpc"
+
+	"github.com/hashicorp/go-plugin"
+
+	"go.woodpecker-ci.org/woodpecker/v2/server/forge"
+)
+
+const pluginKey = "forge"
+
+var HandshakeConfig = plugin.HandshakeConfig{
+	ProtocolVersion:  1,
+	MagicCookieKey:   "WOODPECKER_FORGE_ADDON_PLUGIN",
+	MagicCookieValue: "woodpecker-plugin-magic-cookie-value",
+}
+
+type Plugin struct {
+	Impl forge.Forge
+}
+
+func (p *Plugin) Server(*plugin.MuxBroker) (any, error) {
+	return &RPCServer{Impl: p.Impl}, nil
+}
+
+func (*Plugin) Client(_ *plugin.MuxBroker, c *rpc.Client) (any, error) {
+	return &RPC{client: c}, nil
+}