Refactor to new framework (#98)

- Adjust directory structure
```text
├── internal
│   ├── app
│   │   ├── artifactcache
│   │   ├── cmd
│   │   ├── poll
│   │   └── run
│   └── pkg
│       ├── client
│       ├── config
│       ├── envcheck
│       ├── labels
│       ├── report
│       └── ver
└── main.go
```
- New pkg `labels` to parse label
- New pkg `report` to report logs to Gitea
- Remove pkg `engine`, use `envcheck` to check if docker running.
- Rewrite `runtime` to `run`
- Rewrite `poller` to `poll`
- Simplify some code and remove what's useless.

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/98
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Jason Song <i@wolfogre.com>
Co-committed-by: Jason Song <i@wolfogre.com>

internal/pkg/labels/labels_test.go

@@ -0,0 +1,64 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package labels
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"gotest.tools/v3/assert"
+)
+
+func TestParse(t *testing.T) {
+	tests := []struct {
+		args    string
+		want    *Label
+		wantErr bool
+	}{
+		{
+			args: "ubuntu:docker://node:18",
+			want: &Label{
+				Name:   "ubuntu",
+				Schema: "docker",
+				Arg:    "//node:18",
+			},
+			wantErr: false,
+		},
+		{
+			args: "ubuntu:host",
+			want: &Label{
+				Name:   "ubuntu",
+				Schema: "host",
+				Arg:    "",
+			},
+			wantErr: false,
+		},
+		{
+			args: "ubuntu",
+			want: &Label{
+				Name:   "ubuntu",
+				Schema: "host",
+				Arg:    "",
+			},
+			wantErr: false,
+		},
+		{
+			args:    "ubuntu:vm:ubuntu-18.04",
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.args, func(t *testing.T) {
+			got, err := Parse(tt.args)
+			if tt.wantErr {
+				require.Error(t, err)
+				return
+			} else {
+				require.NoError(t, err)
+			}
+			assert.DeepEqual(t, got, tt.want)
+		})
+	}
+}