This PR includes the following changes:

1. Moves TOML build parsing into a separate module.
2. Corrects the ordering of `apply_*_config` method calls.
3. Moves download logic specific to `toml_config` into its own module.
4. Updates tests to align with the correct behavior.

Author: Shourya742

src/bootstrap/src/core/builder/tests.rs

@@ -1638,6 +1638,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 0 <host> -> LldWrapper 1 <host>
         [build] rustdoc 0 <host>
         [doc] std 1 <host> crates=[core]
         ");
@@ -1653,6 +1654,7 @@ mod snapshot {
                 .render_steps(), @r"
         [build] llvm <host>
         [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustc 0 <host> -> LldWrapper 1 <host>
         [build] rustdoc 0 <host>
         [doc] std 1 <host> crates=[alloc,core]
         ");