19365: bootloaders: fix bootloader button logic r=benpicco a=dylad
### Contribution description
In lastest master, the `BTN_BOOTLOADER_INVERTED` logic doesn't work as expected.
This PR fixes the underlying logic by replacing the `BTN_BOOTLOADER_INVERTED` macro definition by a runtime function.
In fact the current code:
```
#ifndef BTN_BOOTLOADER_INVERTED
#if (BTN0_MODE == GPIO_IN_PD)
#define BTN_BOOTLOADER_INVERTED false
#else
#define BTN_BOOTLOADER_INVERTED true
#endif
#endif
```
cannot work because both `BTN0_MODE` and `GPIO_IN_PD` are not known by the precompiler as they are enum values defined at cpu level.
Thus, replaces it by a runtime function in our bootloader applications.
I've also add `GPIO_OD_PU` along side `GPIO_IN_PU` and add a new define (which can be override at board level or app level) in case an external pullup is used.
### Testing procedure
Flash the riotboot_dfu bootloader:
`make BOARD=saml21-xpro -C bootloaders/riotboot_dfu flash`
Then, flash any test app:
`PROGRAMMER=dfu-util USEMODULE=usbus_dfu make BOARD=saml21-xpro -C tests/shell riotboot/flash-slot0`
With master, the application will not start.
With this PR, the application will start after flashing.
### Issues/PRs references
Fixes#19364
19366: nanocoap_sock: don't include token in empty ACK response r=benpicco a=benpicco
19367: cord: bump reference from draft to rfc r=benpicco a=bergzand
### Contribution description
The draft is an RFC, this bumps the "see also" in the docs to the rfc.
### Testing procedure
Check that the correct RFC is linked in the docs.
### Issues/PRs references
None
Co-authored-by: Dylan Laduranty <dylan.laduranty@mesotic.com>
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Co-authored-by: Koen Zandberg <koen@bergzand.net>
18773: nanocoap_sock: fix handling empty ACKs with separate response r=maribu a=benpicco
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Co-authored-by: Benjamin Valentin <benjamin.valentin@bht-berlin.de>
If a NON confirmable message is sent with a callback function,
not receiving a response in time would lead to a retransmission.
This is of course an error, as only CON messages are to be retransmitted.
The assertion is a bit overeager.
In case of receiving a wrong message ID, we re-try receive without
entering the STATE_REQUEST_SEND state again, so it is expected that
we get a non-NULL ctx/response from sock_udp_recv_buf().
What this assert should actually check is that we don't get a non-NULL
ctx after calling sock_udp_recv_buf() with a non-NULL ctx.
So make this explicit to not falsely fail the assertion.
Some user callbacks might just return the result of some other operation
that returns written bytes or negative error.
Let's not break those, only consider negative callback returns an error.
This removes the need for a user provied work buffer from nanocoap.
Instead we let the user operate directly on network stack internal
memory and provide a callback mechanism to make sure the memory is
properly freed again.
