Switch to upstream protocol for resolving code action

Note that we have to maintain custom implementation on the client
side: I don't see how to marry bulitin resolve support with groups and
snippets.

crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable.txt

@@ -36,7 +36,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -70,6 +69,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },

crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_hint.txt

@@ -36,7 +36,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -70,6 +69,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },

crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_info.txt

@@ -36,7 +36,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -70,6 +69,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },

crates/rust-analyzer/src/diagnostics/test_data/snap_multi_line_fix.txt

@@ -51,7 +51,6 @@
         fixes: [
             CodeAction {
                 title: "return the expression directly",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -98,6 +97,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },

crates/rust-analyzer/src/diagnostics/to_proto.rs

@@ -110,7 +110,6 @@ fn map_rust_child_diagnostic(
     } else {
         MappedRustChildDiagnostic::SuggestedFix(lsp_ext::CodeAction {
             title: rd.message.clone(),
-            id: None,
             group: None,
             kind: Some(lsp_types::CodeActionKind::QUICKFIX),
             edit: Some(lsp_ext::SnippetWorkspaceEdit {
@@ -119,6 +118,7 @@ fn map_rust_child_diagnostic(
                 document_changes: None,
             }),
             is_preferred: Some(true),
+            data: None,
         })
     }
 }