Bring in refactored p2p sentry interface and adjust downloader for it (#1497)

* Initial commit

* Add sentry gRPC interface

* p2psentry directory

* Update README.md

* Update README.md

* Update README.md

* Add go package

* Correct syntax

* add external downloader interface (#2)

* Add txpool (#3)

* Add private API (#4)

* Invert control.proto, add PeerMinBlock, Separare incoming Tx message into a separate stream (#5)

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

* Use new p2psentry interface

* Remove

* Fix lint

* Fix lint

* Separate upload messages into its own stream (#6)

Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>

* Add header upload

* Remove

* Add upload of block headers

* Add block bodies upload

* Fix lint

* Bugfix for blockBodies

* Fix for body upload logging

* Print peerId for GetBlockHeaders

* Invoke block hashes stage to enable block body upload

* Fix test

* Fix stuck bodies download

Co-authored-by: Artem Vorotnikov <artem@vorotnikov.me>
Co-authored-by: b00ris <b00ris@mail.ru>
Co-authored-by: Alexey Sharp <alexeysharp@Alexeys-iMac.local>