[clang-format] Fix incorrect formatting of lambdas inside brace initialisation

[curdeius]

Summary

Fixes https://github.com/llvm/llvm-project/issues/27146.
Fixes https://github.com/llvm/llvm-project/issues/52943.

Before:

namespace ns {

void foo() {
  std::variant<int, double> v;
  std::visit(overloaded{[](auto &&) -> int (*)[] { return nullptr; }}, v);
}

} // namespace ns

int break_me() {
  int x = 42;
  return int{[x = x]() {
    return x;
  }()};
}

got formatted as:

namespace ns {

void foo() {
  std::variant<int, double> v;
  std::visit(overloaded{[](auto &&) -> int (*)[] { return nullptr;
}
} // namespace ns
, v);
}

} // namespace ns

int break_me() {
  int x = 42;
  return int{[x = x](){return x;
}
()
}
;
}

[curdeius]

This patch fixes as well https://github.com/llvm/llvm-project/issues/27146.
Added a test case.

clang/lib/Format/UnwrappedLineParser.cpp

if (FormatTok->isSimpleTypeSpecifier()) {
       continue;
     }
     switch (FormatTok->Tok.getKind()) {
     case tok::l_brace:
       break;
     case tok::l_paren:
       parseParens();
       break;
+    case tok::l_square:
+      parseSquare();
+      break;
     case tok::amp:
     case tok::star:
     case tok::kw_const:
     case tok::comma:
     case tok::less:
     case tok::greater:
     case tok::identifier:
     case tok::numeric_constant:

clang/unittests/Format/FormatTest.cpp

verifyFormat(
       "    });",
       getLLVMStyleWithColumns(70));
   verifyFormat("[]() //\n"
                "    -> int {\n"
                "  return 1; //\n"
                "};");
   verifyFormat("[]() -> Void<T...> {};");
   verifyFormat("[a, b]() -> Tuple<T...> { return {}; };");
+  verifyFormat("SomeFunction({[]() -> int[] { return {}; }});");
+  verifyFormat("SomeFunction({[]() -> int *[] { return {}; }});");
+  verifyFormat("SomeFunction({[]() -> int (*)[] { return {}; }});");
+  verifyFormat("SomeFunction({[]() -> ns::type<int (*)[]> { return {}; }});");
+  verifyFormat("return int{[x = x]() { return x; }()};");
 
   // Lambdas with explicit template argument lists.
   verifyFormat(
       "auto L = []<template <typename> class T, class U>(T<U> &&a) {};\n");
 
   // Multiple lambdas in the same parentheses change indentation rules. These
   // lambdas are forced to start on new lines.
   verifyFormat("SomeFunction(\n"