Don't use numbers larger than will fit into double-precision floating points in the VM Service for identifiers

[DanTup]

The VM Service currently generates random 64bit integers for things like Isolate.number. Some clients (such as JS and Lua) store numbers as double-precision floating point numbers with a max value of 2^53:

https://api.dart.dev/stable/3.0.7/dart-core/int-class.html#:~:text=When%20compiling%20to%20JavaScript

To avoid compatibility issues, it would be better if the VM Service didn't use numbers above 2^53 for these randomly assigned identifiers.

Although in some cases there are string versions of these identifiers, for convenience of clients using both DAP and the VM Service at the same time, we use the Isolate.number in DAP's threadID (which is an integer and we cannot change) so the strings do not help.

(FYI @bkonyi @christopherfujino)

[bkonyi]

This CL will ensure that isolate IDs (along with some other types) will always be valid JS integers.

There will eventually be issues with some other properties being unrepresentable as a JS integer, but I think we have something like > 100,000 years before we have to worry about milliseconds since epoch breaking 2^53-1... :)

[DanTup]

I think we have something like > 100,000 years before we have to worry

Where is the "famous last words" GIF? 🙃

Thanks! :)