[vm] Speedup profile data streaming in AOT

Current implementation of profile data streaming inherited its 
approach to symbolization from the implementation of vm-service's
get{,Perfetto}CpuSamples methods. These methods rather expensive
as they rely on CodeLookupTable to symbolize collected samples, and
constructing CodeLookupTable requires bringing all threads to safepoint
and iterating over old-space to collect code objects. This can take
significant amount of time - especially when old-space is large (e.g.
consider 1Gb+ heaps of Dart Analysis Server).

This CL rewrites profile data streaming to use a completely different
approach in AOT mode where Dart frames are not symbolized eagerly 
and instead stored in the timeline in their raw form: a pair of
an isolate group specific Mapping and a PC value relative to the start
of that mapping. At the end of streaming (or when isolate group
exits) an additional ModuleSymbols packet is emitted which provides
symbolization information for all collected frames. ModuleSymbols
mappings can be cheaply constructed from collected PCs using 
ReversePc lookup tables.

TEST=expanded existing tests

Change-Id: I56ef1dd4c9a17fb0d2e9c24e51f2e4656a6a6964
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/482782
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>