Expose plugin API version and semver compatible check

[leogr]

Motivation

/kind feature Consumers might need to print the supported plugin API version :point_down: https://github.com/falcosecurity/libs/blob/de277bbc1e7a92edc84db9a925fb3e12c7b1cb07/userspace/libscap/plugin_info.h#L30-L32

/kind bug Moreover, we can assume that using semver for version checking is a common expectation of our users. However, the current implementation checks the MAJOR number only :point_down:

https://github.com/falcosecurity/libs/blob/de277bbc1e7a92edc84db9a925fb3e12c7b1cb07/userspace/libsinsp/plugin.cpp#L434-L455

Feature

• Expose the current plugin framework API version (ie. by adding get_plugin_version to scap or sinsp)
• Perform a proper SemVer version check when checking for the plugin compatibility

Alternatives

Considering the simplicity of this solution and assuming semver is a de facto standard, I don't see any other real alternative.

Additional context

[leogr]

/cc @FedeDP

Fede volunteered! :hugs: