Implement generate-auth-secret on beacon node CLI (#10733)

* s

* s

* typo

* typo

* s

* s

* fixes based on PR feedback

* PR feedback

* reverting log changes

* adding flag per feedback

* conventions

* main fixes

* Update cmd/beacon-chain/jwt/jwt.go

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>

* Update cmd/beacon-chain/jwt/jwt.go

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>

* Update cmd/flags.go

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>

* s

* tests

* test attempt

* test

* Update cmd/beacon-chain/jwt/jwt.go

Co-authored-by: Preston Van Loon <preston@prysmaticlabs.com>

* err fix

* s

* further simplify

* cleanup

* namefix

* tests pass

* gaz

* rem deadcode

* Gaz

* shorthand

* naming

* test pass

* dedup

* success

* Ignore jwt.hex file

* logrus

* feedback

* junk

* Also check that no file was written

* local run config

* small fix

* jwt

* testfix

* s

* disabling test

* reverting main changes

* main revert

* removing temp folder

* comment

* gaz

* clarity

* rem

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>
Co-authored-by: Preston Van Loon <preston@prysmaticlabs.com>
Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>
Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

.gitignore

@@ -35,3 +35,6 @@ bin
 
 # p2p metaData
 metaData
+
+# execution API authentication
+jwt.hex