docker serve: parse all remaining mount and VFS options

Before this change, this code implemented an ad-hoc parser for a
subset of vfs and mount options.

After the config re-organization it can use the same parsing code as
the rest of rclone which simplifies the code and exposes all the VFS
and mount options.

cmd/serve/docker/options_test.go

@@ -0,0 +1,75 @@
+package docker
+
+import (
+	"testing"
+	"time"
+
+	"github.com/rclone/rclone/cmd/mountlib"
+	"github.com/rclone/rclone/fs"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	_ "github.com/rclone/rclone/backend/local"
+)
+
+func TestApplyOptions(t *testing.T) {
+	vol := &Volume{
+		Name:       "testName",
+		MountPoint: "testPath",
+		drv: &Driver{
+			root: "testRoot",
+		},
+		mnt: &mountlib.MountPoint{
+			MountPoint: "testPath",
+		},
+		mountReqs: make(map[string]interface{}),
+	}
+
+	// Happy path
+	volOpt := VolOpts{
+		"remote":     "/tmp/docker",
+		"persist":    "FALSE",
+		"mount_type": "potato",
+		// backend options
+		"--local-case-sensitive": "true",
+		"local_no_check_updated": "1",
+		// mount options
+		"debug-fuse":   "true",
+		"attr_timeout": "100s",
+		"--async-read": "TRUE",
+		// vfs options
+		"no-modtime":  "1",
+		"no_checksum": "true",
+		"--no-seek":   "true",
+	}
+	err := vol.applyOptions(volOpt)
+	require.NoError(t, err)
+	// normal options
+	assert.Equal(t, ":local,case_sensitive='true',no_check_updated='1':/tmp/docker", vol.fsString)
+	assert.Equal(t, false, vol.persist)
+	assert.Equal(t, "potato", vol.mountType)
+	// mount options
+	assert.Equal(t, true, vol.mnt.MountOpt.DebugFUSE)
+	assert.Equal(t, fs.Duration(100*time.Second), vol.mnt.MountOpt.AttrTimeout)
+	assert.Equal(t, true, vol.mnt.MountOpt.AsyncRead)
+	// vfs options
+	assert.Equal(t, true, vol.mnt.VFSOpt.NoModTime)
+	assert.Equal(t, true, vol.mnt.VFSOpt.NoChecksum)
+	assert.Equal(t, true, vol.mnt.VFSOpt.NoSeek)
+
+	// Check errors
+	err = vol.applyOptions(VolOpts{
+		"debug-fuse": "POTATO",
+	})
+	require.ErrorContains(t, err, "cannot parse mount options")
+	err = vol.applyOptions(VolOpts{
+		"no-modtime": "POTATO",
+	})
+	require.ErrorContains(t, err, "cannot parse vfs options")
+	err = vol.applyOptions(VolOpts{
+		"remote":          "/tmp/docker",
+		"local_not_found": "POTATO",
+	})
+	require.ErrorContains(t, err, "unsupported backend option")
+
+}