Configurable diff algorithms & new default algorithm

Uses the similar crate to support new diff algorithms:
- Patience (new default)
- Levenshtein (old default)
- Myers
- LCS (Longest Common Subsequence)

Options in "Diff Options" -> "Algorithm..."

Cargo.lock

@@ -2558,6 +2558,7 @@ dependencies = [
  "serde",
  "serde_json",
  "serde_yaml",
+ "similar",
  "tempfile",
  "thiserror",
  "time",
@@ -3362,6 +3363,12 @@ version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d66dc143e6b11c1eddc06d5c423cfc97062865baf299914ab64caa38182078fe"
 
+[[package]]
+name = "similar"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2aeaf503862c419d66959f5d7ca015337d864e9c49485d771b732e2a20453597"
+
 [[package]]
 name = "slab"
 version = "0.4.8"