[lldb] Add Debugger & ScriptedMetadata reference to Platform::CreateInstance

This patch is preparatory work for Scripted Platform support and does
multiple things:

First, it introduces new options for the `platform select` command and
`SBPlatform::Create` API, to hold a reference to the debugger object,
the name of the python script managing the Scripted Platform and a
structured data dictionary that the user can use to pass arbitrary data.

Then, it updates the various `Create` and `GetOrCreate` methods for
the `Platform` and `PlatformList` classes to pass down the new parameter
to the `Platform::CreateInstance` callbacks.

Finally, it updates every callback to reflect these changes.

Differential Revision: https://reviews.llvm.org/D139249



Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>