sage.graphs: Replace imports from sage.*.all for namespace packages

[mkoeppe]

Using ./sage -fiximports from #34945.

Also remove trailing whitespace in the affected files.

Part of Meta-ticket #34201

CC: @alexchandler100 @dcoudert @dimpase

Component: refactoring

Author: Alex Chandler

Branch/Commit: u/mkoeppe/sage_graphs__replace_imports_from_sage___all_for_namespace_packages @ 180c16b

Reviewer: David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/34952

[mkoeppe]

Branch: u/mkoeppe/sage_graphs__replace_imports_from_sage___all_for_namespace_packages

[mkoeppe]

New commits:

180c16b

sage -fiximports src/sage/graphs

[mkoeppe]

Commit: 180c16b

[dcoudert]

comment:3

LGTM.

[dcoudert]

Reviewer: David Coudert

[mkoeppe]

Merged in 10.0.beta0