Add `command_len` argument to the Simple IPC API.
In my original Simple IPC API, I assumed that the request
would always be a null-terminated string of text characters.
The command arg was just a `const char *`.
I found a caller that would like to pass a binary command
to the daemon, so I want to ammend the Simple IPC API to
take `const char *command, size_t command_len` and pass
that to the daemon. (Really, the first arg should just be
a `void *` or `const unsigned byte *` to make that clearer.)
Note, the response side has always been a `struct strbuf`
which includes the buffer and length, so we already support
returning a binary answer. (Yes, it feels a little weird
returning a binary buffer in a `strbuf`, but it works.)
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
fdcc0bc02a