Turn v8_enable_shared_ro_heap on

[ry]

We want to be inline with what default chrome configurations are using to reduce technical debt

rusty_v8/.gn

Lines 48 to 52 in ca83ce5

	# Enabling the shared read-only heap comes with a restriction that all
	# isolates running at the same time must be created from the same snapshot.
	# This is problematic for Deno, which has separate "runtime" and "typescript
	# compiler" snapshots, and sometimes uses them both at the same time.
	v8_enable_shared_ro_heap = false

Problem: there are two snapshots in deno, the main runtime one, and the tsc one. How can we turn this on and also handle both of those? maybe don't snapshot tsc?

[mmastrac]

We might be able to fork before starting the snapshots which might allow us to use two snapshots side-by-side (just not in the same process). The benefit here would likely be a drastic memory reduction for the workers.

[devsnek]

this is enabled now