improve check command and solver problem reporting

[oliverkurth]

Summary

This PR improves tdnf's solver problem reporting to provide full dependency chains for conflicts, making it significantly easier to debug broken dependencies.

Previously, tdnf used solver_findproblemrule which only surfaced the "leaf" problem (e.g., package expect is disabled or conflicting requests), omitting the context of which package actually required it.

Changes Included:

• Enhanced Rule Tracing: Updated SolvReportProblems to use solver_findallproblemrules, traversing and printing the entire chain of dependency rules that lead to a solver failure.
• Verbose Gating: To prevent overly noisy output, the detailed solver traces are gated behind the --verbose flag. Standard output prints the original leaf error alongside a hint: Please retry with --verbose to see detailed solver rules.
• Fixed --skipconflicts Behavior: Addressed an issue where purely conflict-based rules were hidden, but the root install job rule remained, causing unexplainable conflicting requests output. The entire problem block is now correctly suppressed if it is fundamentally a conflict problem.
• Tests: Added pytest coverage in test_install.py to verify the fallback error hint and the detailed reporting behavior.

Example

$ tdnf check --releasever=5.0 --installroot=$(pwd)/installroot
1. package photon-os-installer-2.8-1.ph5.x86_64 requires mkpasswd, but none of the providers can be installed
...
Found 22 problem(s) while resolving
Please retry with --verbose to see detailed solver rules
Error(1301) : Solv general runtime error

$ tdnf check --releasever=5.0 --installroot=$(pwd)/installroot -v
Problem 1:
  - package mkpasswd-5.5.15-2.ph5.x86_64 conflicts with expect provided by expect-5.45.4-4.ph5.x86_64
  - package photon-os-installer-2.8-1.ph5.x86_64 requires mkpasswd, but none of the providers can be installed
  - package dejagnu-1.6.2-3.ph5.noarch requires expect, but none of the providers can be installed
  - job install photon-os-installer-2.8-1.ph5.x86_64 conflicts with other jobs
  - job install dejagnu-1.6.2-3.ph5.noarch conflicts with other jobs