relocate leaflet.esri.clustered-feature-layer to a directory thats less of a mouthful

[jgravois]

hello friends! sorry to be a pain, but i've updated the name of a github repo and npm package while publishing a new version of a leaflet plugin for clustering.

in this PR i am attempting to:

• move the metadata files into a new, more concise directory that matches the npm package name
• update the contents of the files to point at the updated url of the repo
• leave the versions of the library you've already cached where they already are

you can find the contents of my latest tag here:
https://github.com/Esri/esri-leaflet-cluster/tree/v2.0.0/dist

thanks so much for your help!