Cleanup deprecated, make breaking changes for BSC/MSC split
The split into proper BSC/MSC means inevitable backward-incompatible changes to existing configuration. As been discussed in ML, it's a good opportunity to make "spring cleanup" by batching other API/ABI changes together which were postponed as they could break backward compatibility.
This ticket will track such changes, which are not directly related to BSC/MSC split which is tracked in #1845.
- change Kc to uint8_t to support arbitrary lengths
- remove use of all OSMO_DEPRECATED functions