Feat : Admin role to manipulate users

configs/users.json

internal/models/bankAccounts.go

internal/models/bankers.go

internal/models/clients.go

internal/models/models.go

internal/models/operations.go

internal/rootmux/admin_test.go

internal/rootmux/banker_test.go

internal/rootmux/client_test.go

internal/rootmux/rootmux.go

internal/rootmux/rootmux_test.go

internal/rootmux/unlogged_test.go

pkg/auth/oauth2.go