feat: add block explorer

[reecepbcups]

ref: #184

Summary

Adds a block explorer for newly created chains and automatic configuration

Try it out

make install
make template-staking

cd myproject
make sh-testnet

make explorer # docker compose up

TODO

• Get working with localhost (no cors)
• Run in docker instead with nginx config already created? (better UX for actual production). May help with above
• Prompt user to install yarn if not (panic in makefile) w/ echos Dockerfile pingpub and install