Use zig-lsp-codegen (#850)

* add lsp.zig

* change references from types.zig to lsp.zig

* remove types.zig and requests.zig

* add tres as a submodule

* transition codebase from types.zig to lsp.zig

* update lsp.zig

* completely overhaul message handler

* fix memory errors

* partially transition tests to lsp.zig

* update lsp.zig

* more test fixes

* disable failing tests

* fix message handling bugs

* fix remaining tests

* access correct union in diff.applyTextEdits

* more message handler fixes

* run zig fmt

* update tres submodule

* fix memory access to freed memory

* simplify initialize_msg for testing

* check if publishDiagnostics is supported

src/references.zig

@@ -2,7 +2,7 @@ const std = @import("std");
 const Ast = std.zig.Ast;
 const DocumentStore = @import("DocumentStore.zig");
 const analysis = @import("analysis.zig");
-const types = @import("types.zig");
+const types = @import("lsp.zig");
 const offsets = @import("offsets.zig");
 const log = std.log.scoped(.references);
 const ast = @import("ast.zig");