Add runToBinaryEntry option for lldb-vscode

This patch adds a new runToBinaryEntry option which sets a one-shot breakpoint
at program entry. This option is useful for synchronizing module loading with
dynamic loader to measure debugger startup performance:  when program entry
one-short breakpoint hits most of the dependency modules should have been
loaded so this provides a good sample point for debugger startup time.

More explicitly for lldb-vscode, when this option is enabled, "Initialized" DAP
event is synchronously sent after most dependency modules are loaded.

Differential Revision: https://reviews.llvm.org/D135798