Re-structure sat-rs

- Add new shared subcrate satrs-shared to split off some shared
  components not expected to change very often.
- Renmame `satrs-core` to `satrs`. It is expected that sat-rs will remain
  the primary crate, so the core information is superfluous, and core also
  implies stability, which will not be the case for some time.

satrs/src/encoding/mod.rs

@@ -0,0 +1,40 @@
+pub mod ccsds;
+pub mod cobs;
+
+pub use crate::encoding::ccsds::parse_buffer_for_ccsds_space_packets;
+pub use crate::encoding::cobs::{encode_packet_with_cobs, parse_buffer_for_cobs_encoded_packets};
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use alloc::{collections::VecDeque, vec::Vec};
+
+    use crate::tmtc::ReceivesTcCore;
+
+    use super::cobs::encode_packet_with_cobs;
+
+    pub(crate) const SIMPLE_PACKET: [u8; 5] = [1, 2, 3, 4, 5];
+    pub(crate) const INVERTED_PACKET: [u8; 5] = [5, 4, 3, 2, 1];
+
+    #[derive(Default)]
+    pub(crate) struct TcCacher {
+        pub(crate) tc_queue: VecDeque<Vec<u8>>,
+    }
+
+    impl ReceivesTcCore for TcCacher {
+        type Error = ();
+
+        fn pass_tc(&mut self, tc_raw: &[u8]) -> Result<(), Self::Error> {
+            self.tc_queue.push_back(tc_raw.to_vec());
+            Ok(())
+        }
+    }
+
+    pub(crate) fn encode_simple_packet(encoded_buf: &mut [u8], current_idx: &mut usize) {
+        encode_packet_with_cobs(&SIMPLE_PACKET, encoded_buf, current_idx);
+    }
+
+    #[allow(dead_code)]
+    pub(crate) fn encode_inverted_packet(encoded_buf: &mut [u8], current_idx: &mut usize) {
+        encode_packet_with_cobs(&INVERTED_PACKET, encoded_buf, current_idx);
+    }
+}