Tapis Developer Admin Page

[joestubbs]

We need a simple web page where Tapis users/developers can administer aspects of Tapis. This includes:

1. Create and modify OAuth clients using a web form.
2. Generate access tokens including long-lived tokens.

Long-term, it should also link to/include tapis-ui or something similar to allow users to manage other Tapis objects. In particular, "administrative users" will need to do things like manage roles, update configuration of authenticator itself (e.g., for their tenant), update the signing keys, etc. It could also show usage statistics (e.g., unique users in their tenant that have generated an access token).