Update CLI commands to display and use new source resolver config

[smoparth]

Context

After the resolution (Phase 2) and download (Phase 3) dispatches are wired, CLI commands that display or use package configuration need to understand the new source: config.

Parent epic: #1254 (Phase 8)

What needs to happen

package info / _resolve_fromager()

When a package has source: config, display it in the output instead of (or alongside) the legacy resolver_dist / download_source fields.

find-updates / _find_newer_versions()

Use source_resolver.resolver_provider() for resolution when pbi.source_resolver is present. Fall back to legacy path otherwise.

list-overrides

Include packages that have non-default source: config (e.g., provider: github-tag-git) in the overrides listing, since these represent custom source handling.

build / build_sequence()

Ensure the build command's resolution and download steps use the new dispatch (this should mostly work via sources.resolve_source() and sources.download_source() if Phase 2 and 3 are done).

Files

• src/fromager/commands/package.py
• src/fromager/commands/find_updates.py
• src/fromager/commands/list_overrides.py
• src/fromager/commands/build.py

Tests

• package info shows source: config for new-config packages
• find-updates resolves via new system for new-config packages
• list-overrides includes source-config packages
• Legacy-config packages display unchanged

Depends on

• Phase 2: Resolution dispatch
• Phase 3: Download dispatch