major overhaul of Backend from dynamic to static dispatch using an big enum

Cargo.lock

@@ -215,6 +215,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "enum_dispatch"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa18ce2bc66555b3218614519ac839ddb759a7d6720732f979ef8d13be147ecd"
+dependencies = [
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.1"
@@ -395,8 +407,8 @@ dependencies = [
  "anyhow",
  "clap",
  "const_format",
+ "enum_dispatch",
  "libc",
- "pacdef_macros",
  "path-absolutize",
  "regex",
  "rstest",
@@ -409,15 +421,6 @@ dependencies = [
  "walkdir",
 ]
 
-[[package]]
-name = "pacdef_macros"
-version = "1.0.1"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "path-absolutize"
 version = "3.1.1"