[clang-format] Constructor initializer lists format with pp directives

Currently constructor initializer lists sometimes format incorrectly
when there is a preprocessor directive in the middle of the list.
This patch fixes the issue when parsing the initilizer list by
ignoring the preprocessor directive when checking if a block is
part of an initializer list.

rdar://82554274

Reviewed By: MyDeveloperDay, HazardyKnusperkeks

Differential Revision: https://reviews.llvm.org/D109951