Do not create .clangd-format file in project if parent has one

[ghentschke]

In our case, we have a .clang-format file in the root directory of our multi-project git repo. We'd like to use that one instead of having a new .clang_format file being generated for each project. The case looks very similar to issue #227.

In best case, CDT LSP (ClangFormatFileHandler) would check the parent folders to find a .clang-format file, before creating a new one. This way, no customization via additional plug-ins would be necessary for the desired behavior.

Originally posted by @travkin79 in #364 (comment)