Add support for using custom RPC node and chain ID

[jtary]

Currently the RPC node and chain ID are hard-coded into the build file. To enable safer testing, it would be ideal if these values could be picked up from the ENV and overridden in the UI.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Additionally, the meta files could used to get the data for the chain: (eg: https://github.com/ovrclk/net/blob/master/mainnet/meta.json)

[boz]

It's OK to do this after GA IMHO

[anilmurty]

moved to post-ga

[anilmurty]

update, Mar 2nd: @jtary working on implmenting this in the UI under settings.

[anilmurty]

@jtary - could you please create two issues (for the things we talked about in our weekly sync) and reference them here? Even PR references (if you closed them) are fine:

• Found another bug where a new provider’s info doesn’t show up if the provider was spun up while the user session hasn’t been refreshed.
• Also made code changes to the data model for the whole app so that data recoil data (that stores data between pages) refreshes more often.