Add main context closure scheduling

[csnewman]

Changes

Add main context closure scheduling, allowing for advanced use cases (such as ptracing)

[meme]

Thanks for your contribution. LGTM, please ensure it is formatted correctly for CI.

[csnewman]

Updated

[meme]

Looks like some of the symbols you are using have different names on macOS. This is a known issue with the devkits, please add the appropriate symbol aliases in frida-sys' lib.rs.

[csnewman]

Aliases added