Support `import lldb` in a Python interpreter that's different from the one we link against

[JDevlieghere]

When building LLDB agains the Python Limited C ABI [1], it should be possible to do import lldb in a Python interpreter that isn't the same version as the one we built and link against.

• Make LLDB compatible with the Python Limited C API
• Support a Stable ABI LLDB_PYTHON_EXT_SUFFIX
• Fix crash in _PyObject_Malloc

[1] #151617

[llvmbot]

@llvm/issue-subscribers-lldb

Author: Jonas Devlieghere (JDevlieghere)

When building LLDB agains the Python Limited C ABI [1], it should be possible to do `import lldb` in a Python interpreter that isn't the same version as the one we built and link against.

• Make LLDB compatible with the Python Limited C API
• Support a Stable ABI LLDB_PYTHON_EXT_SUFFIX

[1] #151617