[clang-tools-extra] [clangd] Re-land "support outgoing calls in call hierarchy" (PR #117673)

[kadir çetinkaya via cfe-commits]

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@@ -63,6 +63,9 @@ enum class RefKind : uint8_t {
   //   ^ this references Foo, but does not explicitly spell out its name
   // };
   Spelled = 1 << 3,
+  // A reference which is a call. Used as a filter for which references
+  // to store in data structures used for computing outgoing calls.
+  Call = 1 << 4,
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kadircet wrote:

FWIW, this isn't a backward incompatible change, but if you want background-index shards to catch up, we should update version in `index/Serialization.cpp`.

https://github.com/llvm/llvm-project/pull/117673