dev branch: check if a provider supports a refresh token scope

Some OpenID Connect providers, notably Google, don't follow the spec
and allow refresh tokens to be requested with the "offline_access"
scope. Try to determine which we're talking to by checking the
supported_scopes listed by the provider discovery.

dev branch: expose skip approval screen option

server: fix cross client scope prefix

dev branch: add a password resource for local email/password login

dev branch: prepare build scripts for a release

storage: increase the number of bytes randomly generated for IDs

dev branch: add a simple gRPC API

server: add a test for the health check handler

storage/sql: enable garbage collection

Was an oversite of the initial SQL PR.

Because these values are used for OAuth2 codes, refresh tokens,
etc, they shouldn't be guessable. Increase the number of random
bytes from 64 to 128.

cmd/dex: rename file

dev branch: add SQL storage implementation