Show the source of conflicting dependencies

[zanieb]

When dependencies directly conflict, we should show which file we loaded them from.

e.g.

× No solution found when resolving dependencies:
╰─▶ Because you require filelock==1.0.0 and you require filelock==3.8.0, we
    can conclude that the requirements are unsatisfiable.

from compile_constraints_incompatible_version could say

× No solution found when resolving dependencies:
╰─▶ Because you require filelock==1.0.0 (from requirements.txt) and you require filelock==3.8.0 (from constraints.txt), we
    can conclude that the requirements are unsatisfiable.

Originally mentioned at https://github.com/astral-sh/uv/pull/1796/files#r1498258800