Complete preliminary find and replace rules

Tested by replacing AJR with John Van Derwood. Need to test on albums and artists, as well as matching on one piece of metadata, and replacing another

src/types.zig

@@ -38,23 +38,23 @@ pub const SpotifyScrobble = struct {
 const Rule = struct {
     name: []const u8,
     conditionals: []struct {
-        match_on: MatchOn,
+        match_on: ScrobbleFields,
         match_cond: enum { is, contains },
         match_txt: []const u8,
     },
     actions: []struct {
-        action: []const u8,
-        action_on: enum { is, contains },
+        action: enum { replace, add },
+        action_on: ScrobbleFields,
         action_txt: []const u8,
     },
 };
 
-const Rules = struct {
+pub const Rules = struct {
     rules: []const Rule,
 };
 
-const MatchOn = enum {
+pub const ScrobbleFields = enum {
     artist,
     album,
-    song,
+    track,
 };