Static testnet configs (#1603)

## Issue Addressed

#1431 

## Proposed Changes

Added an archived zip file with required files manually

## Additional Info

1) Used zip, instead of tar.gz to add a single dependency instead of two.
2) I left the download from github code for now, waiting to hear if you'd like it cleaned up or left to be used for some tooling needs.

common/eth2_testnet_config/.gitignore

@@ -1,4 +1,4 @@
-testnet*
+testnet*/*
 schlesi-*
 witti-*
 altona*