Update syn crate from 1.0.109 to 2.0.101 (#31301)

Nearly all generated by Zed Agent + Claude Opus 4. I just wrote the test
`Args` struct and pointed it at the [2.0 release
notes](https://github.com/dtolnay/syn/releases/tag/2.0.0).

Release Notes:

- N/A

Cargo.lock

@@ -4351,7 +4351,7 @@ version = "0.1.0"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 1.0.109",
+ "syn 2.0.101",
  "workspace-hack",
 ]
 
@@ -7125,7 +7125,7 @@ dependencies = [
  "gpui",
  "proc-macro2",
  "quote",
- "syn 1.0.109",
+ "syn 2.0.101",
  "workspace-hack",
 ]
 
@@ -14757,7 +14757,7 @@ version = "0.1.0"
 dependencies = [
  "sqlez",
  "sqlformat",
- "syn 1.0.109",
+ "syn 2.0.101",
  "workspace-hack",
 ]
 
@@ -16842,7 +16842,7 @@ name = "ui_macros"
 version = "0.1.0"
 dependencies = [
  "quote",
- "syn 1.0.109",
+ "syn 2.0.101",
  "workspace-hack",
 ]
 
@@ -17099,7 +17099,7 @@ name = "util_macros"
 version = "0.1.0"
 dependencies = [
  "quote",
- "syn 1.0.109",
+ "syn 2.0.101",
  "workspace-hack",
 ]