Add a command version field on the interaction's application command data

[freya022]

Adding a version or command_version field in the interaction's application command data would allow us to check if the version of a command is the same with what the bot has registered.

My use case is that my bot saves the command data in-memory, and on disk, to avoid doing requests on every restart.
Currently it looks for the command ID, but this isn't enough to truly know if the command it receives is the command it knows about, as the user could have modified the command, but kept the same command ID, which is why sending the command version would be beneficial.

Similarly, a bot that saves the data in-memory after pushing their commands, can check when receiving a command to ensure that it should be able to read the data it expects.

In both cases, it's additional safety in case you accidentally override your commands.