Add a breakpoint override resolver feature to lldb (#195392)

This is a general mechanism that allows a custom breakpoint resolver to
"override" the resolver lldb would have used. It is implemented by
making a scripted breakpoint resolver class, implementing an extra
"overrides_resolver" method. When lldb has decided what resolver it is
going to use for the breakpoint, if there are any override resolvers
registered, it will pass the serialized form of the resolver to the
`overrides_resolver` method of the registered resolvers. If any of the
override resolvers return true from the overrides_resolver method, that
resolver will be used in place of the one lldb would have used.

The original motivation for this feature is to make the support of
"debugging a scripting language from the implementation side". We added
the notion of "facade breakpoints" so that a location given in the
context of the scripting language can be handled by the emulation code.
But when you are using lldb in some IDE, when "stopped" in the scripting
language, the IDE will show the scripting language source. It is natural
in that case for the user to expect the UI gesture to set a file and
line breakpoint should work the same way.

To implement that, the implementor would make their facade breakpoint
resolver also an override resolver that checks to see if the incoming
resolver was a file and line breakpoint for a source file of the
scripting language type. If it is, it returns true, and lldb will use
that resolver instead. Note, this will also work when breakpoints are
set on the command line, so you can transparently support "scripting
language" breakpoints from the command line as well.