Add Firefox Dump extension

[moloch--]

Summary

Add the Firefox Dump Sliver extension backed by the signed immutable v0.0.2 package release:

• command: firefoxdump
• package: https://github.com/sliverarmory/firefoxdump
• release: https://github.com/sliverarmory/firefoxdump/releases/tag/v0.0.2
• Minisign public key fingerprint: 5F96BC3ABC5BEF13
• executor: built-in Reflektor only, with no coff-loader fallback

Compatibility boundary

The package requires Sliver client, server, and implant builds from b19e383111dbf8b04096806b249f6238274edff4 or later. No currently published stable Sliver release contains that built-in BOF path, so older components fail closed rather than falling back.

Validation

• anonymous public asset download succeeded
• package Minisign signature verified with the indexed key
• trusted comment exactly equals the archived extension manifest
• Windows amd64 and 386 COFF mappings validated
• package workflow and both native Reflektor execution jobs passed on the release commit
• validate_index.py against signed index v0.0.45 reports no new issues; three historical baseline issues remain
• the diff is one armory.json entry

This branch is based on current master, including the already-reviewed PowerChell entry; this PR does not modify PowerChell.