Add functionality for installing extensions

[ehennestad]

Motivation

Provide an easy way to install extensions from the Neurodata Extension Catalog in matnwb.

How to test the behavior?

nwbInstallExtension("ndx-miniscope")

Todo

• Write tests
• Workflow for updating nwbInstallExtension if the records of the Neurodata Extension Catalog has been updated
• Set up deploy keys and allow GitHub Actions to write to main branch using deploy key
• Set up external trigger from nwb-extensions.github.io
• Add link to https://nwb-extensions.github.io in the doctring of nwbInstallExtension

Checklist

• Have you ensured the PR description clearly describes the problem and solutions?
• Have you checked to ensure that there aren't other open or previously closed Pull Requests for the same change?
• If this PR fixes an issue, is the first line of the PR description fix #XX where XX is the issue number?