Allow dynamic key reloading when having inactive keys (imported & derived) (#8119)

* restart waiting for activation on key change

* test fixes

* wiat for activation comments

* regression test

* log fatal when validator cast fails

* derived keymanager

* review comments

* add buffer to channel

* simplify key refetch logic

* reload keys into empty wallet

* removed warning on wallet creation

* add empty line

* export AccountsKeystoreRepresentation type

* unit test for handleAccountsChanged

* test ctx cancellation

* add missing mockRemoteKeymanager interface function

* gazelle

* gzl

* fix panic inside goroutine during runner tests

* rename error message variables

* Update validator/accounts/accounts_list_test.go

* reorder imports

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

validator/keymanager/BUILD.bazel

@@ -13,6 +13,7 @@ go_library(
     deps = [
         "//proto/validator/accounts/v2:go_default_library",
         "//shared/bls:go_default_library",
+        "//shared/event:go_default_library",
     ],
 )