pagectl: key command for dumping what we know about the key (#7890)

What we know about the key via added `pagectl key $key` command:
- debug formatting
- shard placement when `--shard-count` is specified
- different boolean queries in `key.rs`
- aux files v2

Example:

```
$ cargo run -qp pagectl -- key 000000063F00004005000060270000100E2C
parsed from hex: 000000063F00004005000060270000100E2C:

Key { field1: 0, field2: 1599, field3: 16389, field4: 24615, field5: 0, field6: 1052204 }
rel_block:         true
rel_vm_block:      false
rel_fsm_block:     false
slru_block:        false
inherited:         true
rel_size:          false
slru_segment_size: false
recognized kind:   None
```

libs/utils/src/hex.rs

@@ -19,13 +19,13 @@
 /// // right: [0x68; 1]
 /// # fn serialize_something() -> Vec<u8> { "hello world".as_bytes().to_vec() }
 /// ```
-#[derive(PartialEq)]
-pub struct Hex<'a>(pub &'a [u8]);
+pub struct Hex<S>(pub S);
 
-impl std::fmt::Debug for Hex<'_> {
+impl<S: AsRef<[u8]>> std::fmt::Debug for Hex<S> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "[")?;
-        for (i, c) in self.0.chunks(16).enumerate() {
+        let chunks = self.0.as_ref().chunks(16);
+        for (i, c) in chunks.enumerate() {
             if i > 0 && !c.is_empty() {
                 writeln!(f, ", ")?;
             }
@@ -36,6 +36,15 @@ impl std::fmt::Debug for Hex<'_> {
                 write!(f, "0x{b:02x}")?;
             }
         }
-        write!(f, "; {}]", self.0.len())
+        write!(f, "; {}]", self.0.as_ref().len())
+    }
+}
+
+impl<R: AsRef<[u8]>, L: AsRef<[u8]>> PartialEq<Hex<R>> for Hex<L> {
+    fn eq(&self, other: &Hex<R>) -> bool {
+        let left = self.0.as_ref();
+        let right = other.0.as_ref();
+
+        left == right
     }
 }