**What type of PR is this?**
Feature
**What does this PR do? Why is it needed?**
implements the new GET /eth/v4/validator/blocks/{slot} endpoint, we
don't hook up the validator client to use it yet for post gloas in this
pr.
**Which issues(s) does this PR fix?**
Fixes https://github.com/ethereum/beacon-APIs/pull/580
**Other notes for review**
**Acknowledgements**
- [x] I have read
[CONTRIBUTING.md](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md).
- [x] I have included a uniquely named [changelog fragment
file](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md#maintaining-changelogmd).
- [x] I have added a description with sufficient context for reviewers
to understand this PR.
- [x] I have tested that my changes work as expected and I added a
testing plan to the PR description (if applicable).
* sse implementation that sheds stuck clients
* Radek and James feedback
* Refactor event streamer code for readability
* less-flaky test signaling
* test case where queue fills; fixes
* add changelog entry
* james and preston feedback
* swap our Subscription interface with an alias
* event.Data can be nil for the payload attr event
* deepsource
---------
Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>
* Initial code for head event streaming
* handle events and error
* keepalive event
* tests
* generate new mock
* remove single case select
* cleanup
* explain eventByteLimit
* use 2 channels in test
* review
* more review
---------
Co-authored-by: james-prysm <90280386+james-prysm@users.noreply.github.com>
* adding in block rewards to represent consensus payload
* Update beacon-chain/rpc/eth/validator/handlers_block.go
Co-authored-by: Radosław Kapka <rkapka@wp.pl>
* radek's comments
* more review changes
* adding more tests for forks
* gaz
* updating names
* gaz
* fixing imports
* fixing variable name
* gaz
* fixing test
* renaming variables to match data
---------
Co-authored-by: Radosław Kapka <rkapka@wp.pl>
