Use git dependency for asap_sketchlib and fix build against Sketchlib main

[milindsrivastava1997]

asap-precompute-rs depends on Sketchlib via a relative path:

asap_sketchlib = { path = "../../asap_sketchlib" }

Downstream repos that consume Collector from git (e.g. ASAPQuery-backend) can't resolve this and need a [patch."https://github.com/ProjectASAP/ASAPCollector"] workaround.

Also, asap-precompute-rs doesn't build against current Sketchlib main (932ab4a):

error[E0063]: missing fields `negative_store_counts`, `negative_store_offset` and `zero_count` in initializer of `DdSketchState`

Fix

• Switch to asap_sketchlib = { git = "https://github.com/ProjectASAP/asap_sketchlib" } (bare URL, no branch/rev, so it unifies with other consumers).
• Update the DdSketchState initializer for the new fields.
• For local Sketchlib development, use an untracked .cargo/config.toml [patch] pointing at the local checkout.