Todd Gamblin 6753cc0b81 refactor: Index provided virtuals by when spec ...

Part 4 of reworking all package metadata to key by `when` conditions.

Changes conflict dictionary structure from this:

    { provided_spec: {when_spec, ...} }

to this:

    { when_spec: {provided_spec, ...} }

2024-01-09 00:26:22 -08:00

..

spack

refactor: Index provided virtuals by when spec

2024-01-09 00:26:22 -08:00