feat: Use ets for last-known server-time.#136

kinyoklion merged 13 commits intomainlaunchdarkly/erlang-server-sdk:mainfrom

rlamb/SDK-677/move-get-last-server-time-to-etslaunchdarkly/erlang-server-sdk:rlamb/SDK-677/move-get-last-server-time-to-etsCopy head branch name to clipboard