Re-land LLDB dap module symbol tables (#155021)
Re-land the symbol table feature in lldb-dap after it was
[reverted](https://github.com/llvm/llvm-project/commit/2b8e80694263fb404d1d0b816f33df731e617625)
because of a crash in the `aarch64` tests, which was caused by
dereferencing `SBSymbol::GetName` which might return `nullptr` for an
invalid symbol.
This patch reapplies the original commits and adds the missing null
check.
Also adding `skipIfWindows` for the module symbols tests, since LLDB
doesn't recognize the symbols from a.out there.
