Fix typos

[srak289]

Noticed these typos while reading through source looking at other things so I wrote a test layout to cause the error.

  File "/home/srak/projects/carthage/carthage/modeling/decorators.py", line 258, in handle
    super().handle(cls, ns, k. state)
                            ^^^^^^^^
AttributeError: 'str' object has no attribute 'state'

After fixing the above error another error was raised:

File "/home/srak/projects/carthage/carthage/modeling/decorators.py", line 259, in handle
    state.flags &= ~(NSFlags.inject_by_name | NsFlags.inject_by_class | NSFlags.instantiate_on_access)
                                              ^^^^^^^
NameError: name 'NsFlags' is not defined. Did you mean: 'NSFlags'?

The below code will cause these errors to be raised:

class Layout(CarthageLayout):

    layout_name = "test"

    domain = "somedomain.net"

    add_provider(machine_implementation_key, dependency_quote(BareMetalMachine))

    @machine_mixin(name="proxy")
    class nginx_install_mixin(MachineModel):
        class nginx_customization(MachineCustomization):

            @setup_task("install nginx")
            async def install_nginx(self):
                print("installing nginx")
                return "nginx was installed"

            @install_nginx.check_completed()
            async def install_nginx(self):
                return True

    class proxy(MachineModel):
        name = "proxy"