Add support for TOML files (#633)

TOML maps well to Lua, is easier to read and write than JSON, and is
commonly used by Roblox tools.

Use cases:
* Put game, plugin, or library config in a toml file
* Sync in toml files generated by tools
* Sync in config files for tools so that the game can double-check that
the config file has been followed. (e.g. check that packages match
versions specified in wally.toml)

src/snapshot_middleware/mod.rs

@@ -14,6 +14,7 @@ mod meta_file;
 mod project;
 mod rbxm;
 mod rbxmx;
+mod toml;
 mod txt;
 mod util;
 
@@ -32,6 +33,7 @@ use self::{
     project::snapshot_project,
     rbxm::snapshot_rbxm,
     rbxmx::snapshot_rbxmx,
+    toml::snapshot_toml,
     txt::snapshot_txt,
     util::PathExt,
 };
@@ -117,6 +119,8 @@ pub fn snapshot_from_vfs(
             return Ok(None);
         } else if path.file_name_ends_with(".json") {
             return snapshot_json(context, vfs, path);
+        } else if path.file_name_ends_with(".toml") {
+            return snapshot_toml(context, vfs, path);
         } else if let Ok(name) = csv_name {
             match name {
                 // init csv are handled elsewhere and should not turn into