wip: auth with mock OAuth2

.vscode/launch.json

dev_certificates/RootCA.crt

dev_certificates/RootCA.key

dev_certificates/RootCA.pem

dev_certificates/RootCA.srl

dev_certificates/domains.ext

dev_certificates/generate-certificates.sh

dev_certificates/localhost.crt

dev_certificates/localhost.csr

dev_certificates/localhost.key

go.mod

go.sum

internal/auth/auth.go

internal/auth/oauth2.go

internal/common/common.go

internal/common/common_test.go

internal/mocks/mocks.go

internal/rootmux/rootmux.go

internal/tokens/tokens.go

internal/tokens/tokens_test.go