Adapt llvm 22 changes

indexer: Resolve the type alias correctly (#988)

Add clang.prependArgs option

indexer: Support Decl::Concept

index_tests: Test 22.0.0git

index: remove unused SemaManager parameter

Accommodate changes of LLVM 21 & 22 to fix builds (#985)

Adapt llvmorg-21 changes: clang::CompilerInstance and llvm::PointerUnion

Clear index requests upon "exit"

Reformat all the files after 192a82b (#979)

Adapt llvmorg-20-init-12964-gdf9a14d7bbf1: createDiagnostics

textDocument/signatureHelp: add trigger character {

Implement textDocument/switchSourceheader

Support LSP semantic tokens

Drop support for LLVM 7, 8, and 9