feat: detect potential incremental routes and bruteforce them

[Ullaakut]

Goal of this PR

Fixes #263

Adds support for detecting “incrementable” RTSP routes (e.g., ChannelID patterns) and automatically brute-forcing sequential variants to discover additional streams on the same target.

Changes

• Introduces incremental-route parsing/building helpers to identify and increment numeric route segments (with channel-oriented heuristics).
• Extends the attacker to attempt incremental route discovery after finding a working route and/or valid credentials (while avoiding duplicate routes).

How did I test it?

Unit test coverage was added, but I can't do a proper end to end test myself:

• RTSPATT only supports exposing a single route per ip/port combo
• I no longer own CCTV cameras that I could configure to replicate this

[Ullaakut]

In the end, implementing this feature in a safe and correct way introduces much more complexity than I initially anticipated. No longer sure it's worth the maintenance/cognitive complexity cost to include it. Might keep this one on hold unless I see more interest for it. Especially given that it could be replaced by just writing a script to generate a dictionary with incremental channel IDs for the routes 🤔