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/mode.rs

@@ -0,0 +1,94 @@
+use crate::tmtc::TargetId;
+use core::mem::size_of;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+use spacepackets::ByteConversionError;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct ModeAndSubmode {
+    mode: u32,
+    submode: u16,
+}
+
+impl ModeAndSubmode {
+    pub const fn new_mode_only(mode: u32) -> Self {
+        Self { mode, submode: 0 }
+    }
+
+    pub const fn new(mode: u32, submode: u16) -> Self {
+        Self { mode, submode }
+    }
+
+    pub fn raw_len() -> usize {
+        size_of::<u32>() + size_of::<u16>()
+    }
+
+    pub fn from_be_bytes(buf: &[u8]) -> Result<Self, ByteConversionError> {
+        if buf.len() < 6 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                expected: 6,
+                found: buf.len(),
+            });
+        }
+        Ok(Self {
+            mode: u32::from_be_bytes(buf[0..4].try_into().unwrap()),
+            submode: u16::from_be_bytes(buf[4..6].try_into().unwrap()),
+        })
+    }
+
+    pub fn mode(&self) -> u32 {
+        self.mode
+    }
+
+    pub fn submode(&self) -> u16 {
+        self.submode
+    }
+}
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct ModeCommand {
+    pub address: TargetId,
+    pub mode_submode: ModeAndSubmode,
+}
+
+impl ModeCommand {
+    pub const fn new(address: TargetId, mode_submode: ModeAndSubmode) -> Self {
+        Self {
+            address,
+            mode_submode,
+        }
+    }
+
+    pub fn address(&self) -> TargetId {
+        self.address
+    }
+
+    pub fn mode_submode(&self) -> ModeAndSubmode {
+        self.mode_submode
+    }
+
+    pub fn mode(&self) -> u32 {
+        self.mode_submode.mode
+    }
+
+    pub fn submode(&self) -> u16 {
+        self.mode_submode.submode
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum ModeRequest {
+    SetMode(ModeAndSubmode),
+    ReadMode,
+    AnnounceMode,
+    AnnounceModeRecursive,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct TargetedModeRequest {
+    target_id: TargetId,
+    mode_request: ModeRequest,
+}