refactor: improve async extraction with automatic activation and benchmarks

[jasondellaluce]

What type of PR is this?

/kind feature

Any specific area of the project related to this PR?

/area plugin-sdk

What this PR does / why we need it: For deeper context, see https://github.com/falcosecurity/plugin-sdk-go/issues/25. This PR improves async extraction by:

• Adding a reproducible benchmark suite, which helped us understanding how to improve the async worker
• Adding an automatic feasibility detection based on the number of CPUs. For now, async extraction is available if at least two CPUs are available.
• Enabling async extraction by default (if feasible), and allowing plugin developers to disable/enable it during the plugin initialization.
• Improving the async worker by using a shared spinlock between the C and Go runtimes. This avoids the need of a Go -> C call that was previously used to synchronize the worker.

Which issue(s) this PR fixes:

Fixes #25

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

refactor: improve async extraction with automatic activation and benchmarks

[poiana]

LGTM label has been added.

Git tree hash: 1d3990b8089b4ca1c9eef24c5bb77a486279fe1e

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jasondellaluce, leogr

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/falcosecurity/plugin-sdk-go/blob/main/OWNERS)~~ [jasondellaluce,leogr] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment