feat: Use BPF iterator instead of procfs

[vadorovsky]

Replace the process tracker initialization process from procfs parsing to BPF iterators, which are less erronous and result in an easier implementation.

[Copilot]

Pull Request Overview

This PR replaces the process tracker initialization from procfs parsing to a BPF iterator approach to improve reliability and simplify the implementation.

• Introduces a new enum ContainerEngineKind in pulsar-core to represent container engines.
• Removes the duplicate ContainerEngineKind from process-monitor and updates the process tree loading logic to use BPF iterator output.
• Updates the initializer to use the new process tree loader and changes the aya dependency configuration in Cargo.toml.

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/pulsar-core/src/event.rs	Added ContainerEngineKind enum for container engine distinction.
crates/modules/process-monitor/src/lib.rs	Updated import statements by removing duplicate enum definition.
crates/bpf-filtering/src/process_tree.rs	Replaced procfs parsing with reading from a BPF iterator and updated error handling for incorrect output formats.
crates/bpf-filtering/src/initializer.rs	Updated process tree initialization to use the new BPF iterator loader.
Cargo.toml	Updated aya dependency to a specific git revision.

Files not reviewed (1)

• crates/modules/process-monitor/probes.bpf.c: Language not supported