feat: enable pipstar by default

[aignas]

This is just a laundry list for the flag to be flipped by default and enable better dependency graph construction using the marker settings.

• Add expressions_any to the env_marker_setting macro so that we can create many targets under the hood so that each FeatureFlagInfo producing target would be processing smaller expressions. At the moment we just do (expr1) or (expr2) or ... combination, which feel like it may make the tokenizing more nested and we cannot short-circuit early unless we improve the parser.
• Wait for the Improve the pip.parse API to allow for incremental building of the configuration #2747 to be finished so that users can have levers to pull to configure the env marker evaluation when parsing requirements files.
• Enable pipstar by default in rules_python CI
• Ask users to test pipstar in isolation before the next release.
• (optional) add an example in the documentation how to configure platform_version and similar?

Am I missing some steps?