fix(exo): reform exo amplifier API

[erights]

closes: #XXXX
refs: #1902

Description

At #1902 (comment) @mhofman rightly points out

In the kernel meeting a couple weeks ago, we discussed having the shape of this rights amplification function be a simple function that accepts a facet, and returns the cohort. I think I preferred that shape vs taking a facet name, but I do realize I didn't capture that feedback in this pull request.

This PR fixes that oversight.

Security Considerations

Scaling Considerations

Documentation Considerations

Testing Considerations

Upgrade Considerations

I flagged this PR with a fix(exo)!: ... because this fix is not a compat change from #1902. OTOH, it is unlikely that anyone is using the #1902 API yet, in which case this PR is a compat change from the prior endo state. The last endo release was before #1902, so this PR is also a compat change from the last release.

Should I downgrade to fix(exo): ... ?

[mhofman]

Should I downgrade to fix(exo): ...

IMO Yes

[mhofman]

Besides some typing and comment nits, LGTM. Please downgrade the "breaking" conventional commit down to a regular fix given that no release has been made since the feature was introduced.

[erights]

Besides some typing and comment nits, LGTM. Please downgrade the "breaking" conventional commit down to a regular fix given that no release has been made since the feature was introduced.

Done