v4: Rename inconsistent public APIs

[jtdub]

Description

Several public API names don't follow Python conventions or are unclear:

Current	Proposed	Reason
tags_add() / tags_remove()	add_tags() / remove_tags()	Python convention
depth() method	depth property	Consistent with is_leaf, is_branch
cisco_style_text()	formatted_text() or indented_text()	Not Cisco-specific
dump_simple()	to_lines() or render()	Clearer intent
config_to_get_to()	remediation(target) or diff_to(target)	Current name is hard to parse

Breaking Change

Yes — all renamed methods would break existing code. Provide deprecation aliases in a 3.x release if feasible.

[jtdub]

Implemented in ea09a9d on the next branch. All renames complete: tags_add/tags_remove → add_tags/remove_tags, cisco_style_text → indented_text, dump_simple → to_lines, config_to_get_to → remediation, depth() → depth property.