[clang] [clang-tools-extra] [clangd][clang-tidy] Factor out mergeFixits() logic and reuse it in clangd (PR #208682)

[Nathan Ridge via cfe-commits]

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@@ -807,13 +807,23 @@ void StoreDiags::HandleDiagnostic(DiagnosticsEngine::Level DiagLevel,
         return false;
       if (!isInsideMainFile(FixIt.RemoveRange.getBegin(), SM))
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HighCommander4 wrote:

Since we're checking this for the merged fixits, let's not check it in duplicate here

https://github.com/llvm/llvm-project/pull/208682