Add vk bridge (#1372)

* Add vk bridge

* Vk bridge attachments

* Vk bridge forwarded messages

* Vk bridge sample config and code cleanup

* Vk bridge add vendor

* Vk bridge message edit

* Vk bridge: fix fetching names of other bots

* Vk bridge: code cleanup

* Vk bridge: fix shadows declaration

* Vk bridge: remove UseFileURL

vendor/github.com/SevereCloud/vksdk/v2/longpoll-bot/context.go

@@ -0,0 +1,12 @@
+package longpoll // import "github.com/SevereCloud/vksdk/v2/longpoll-bot"
+
+import (
+	"context"
+
+	"github.com/SevereCloud/vksdk/v2/internal"
+)
+
+// TsFromContext returns the ts from context.
+func TsFromContext(ctx context.Context) int {
+	return ctx.Value(internal.LongPollTsKey).(int)
+}