Resolve "Pickpocket a falador guard - Falador achievement cannot be done."

What have you done in this MR?

• Implemented Diary task for Pickpocketing a Falador Guard by:

1. Implementing a map area to avoid false positives
2. Adding Guard IDs to private val FALADOR_GUARD to capture 4 varieties of guard
3. Capturing the pickpocket event and on success within the correct area, awarding the diary achievement.

Are there any tricky things testers should keep an eye out for?

• No
• Yes, as follows:

It's worth noting that:

• It would be a good idea to peer-review if the boundaries of the area in which this can be proc'd are reasonable. Currently set to:

• I have tested these changes thoroughly.

• This requires extra testing due to changes to architecture or other similarly risky changes.

• I used the Thanos Tool for any JSON edits where possible, and have attached screenshots of any changes.

• I acknowledge that this contribution will be released under the AGPL license.

Closes #889 (closed)