Tidy up log messages across the codebase

1. Clearly separate the log messages from any fields that are
captured. The log message itself should be meaningful because it
depends on the underlying formatter, how/if the fields are displayed.
2. Some log messages had very little context, expand that.
3. Wording of errors was inconsistent, hopefully all errors should
now start with `Failed to ...`.
4. Some log messages were duplicated across multiple layers (like opening
the database).
5. Some log messages were split into two where one part is now an `error!`
and the 2nd part is an `info!` on what is happening next.
6. Where appropriate, punctuation has been removed to not interrupt
the reader's flow.

swap/src/bitcoin/lock.rs

@@ -151,14 +151,14 @@ impl TxLock {
             witness: Vec::new(),
         };
 
-        let spending_fee = spending_fee.as_sat();
-        tracing::debug!(%spending_fee, "Redeem tx fee");
+        let fee = spending_fee.as_sat();
         let tx_out = TxOut {
-            value: self.inner.clone().extract_tx().output[self.lock_output_vout()].value
-                - spending_fee,
+            value: self.inner.clone().extract_tx().output[self.lock_output_vout()].value - fee,
             script_pubkey: spend_address.script_pubkey(),
         };
 
+        tracing::debug!(%fee, "Constructed Bitcoin spending transaction");
+
         Transaction {
             version: 2,
             lock_time: 0,