chore!(amneziawg): refactor to be separate from wireguard

- amneziawg is now a VPN protocol and no longer a Wireguard implementation
- Use it with VPN_TYPE=amneziawg
- document AMNEZIAWG_* options in Dockerfile
- document amneziawg support in readme
- separate amneziawg settings and code from wireguard
- re-use code from wireguard whenever possible

internal/wireguard/cleanup_test.go

@@ -1,57 +0,0 @@
-package wireguard
-
-import (
-	"errors"
-	"testing"
-
-	"github.com/golang/mock/gomock"
-	"github.com/stretchr/testify/assert"
-)
-
-func Test_closers(t *testing.T) {
-	t.Parallel()
-
-	ctrl := gomock.NewController(t)
-
-	var ACloseCalled, BCloseCalled, CCloseCalled bool
-	var (
-		AErr error
-		BErr = errors.New("B failed")
-		CErr = errors.New("C failed")
-	)
-
-	var closers closers
-	closers.add("closing A", stepFive, func() error {
-		ACloseCalled = true
-		return AErr
-	})
-
-	closers.add("closing B", stepThree, func() error {
-		BCloseCalled = true
-		return BErr
-	})
-
-	closers.add("closing C", stepTwo, func() error {
-		CCloseCalled = true
-		return CErr
-	})
-
-	logger := NewMockLogger(ctrl)
-	prevCall := logger.EXPECT().Debug("closing C...")
-	prevCall = logger.EXPECT().Error("failed closing C: C failed").After(prevCall)
-	prevCall = logger.EXPECT().Debug("closing B...").After(prevCall)
-	prevCall = logger.EXPECT().Error("failed closing B: B failed").After(prevCall)
-	logger.EXPECT().Debug("closing A...").After(prevCall)
-
-	closers.cleanup(logger)
-
-	closers.cleanup(logger) // run twice should not close already closed
-
-	for _, closer := range closers {
-		assert.True(t, closer.closed)
-	}
-
-	assert.True(t, ACloseCalled)
-	assert.True(t, BCloseCalled)
-	assert.True(t, CCloseCalled)
-}