Convert kik Users-in-Groups + Local Account to artifact_processor (LAVA)

[abrignoni]

Summary

First cluster PR of the iLEAPP modernization (following the medicalID pilot, #1552). Converts the two simple kik.sqlite user/group artifacts together — they share the same source and query shape, have no protobuf and no media.

Artifact	Report
kikUsersgroups	Kik Users in Groups
kikLocaladmin	Kik Local Account

kikGroupadmins (blackboxprotobuf decoding) and the media-bearing kik artifacts (kikMessages, kikBplistmeta) are deliberately not in this PR — they'll get their own.

Changes

• v1 __artifacts__ → __artifacts_v2__; @artifact_processor with the 5-arg iLEAPP signature (unused args underscore-prefixed → pylint 10.00, no disable header per house style).
• Robust source selection: iterate files_found + endswith('kik.sqlite') with an empty-guard (no files_found[0]).
• Bug fix: the per-row group sub-query left grouptag/groupdname/zjid/zpurl undefined when it returned no rows (NameError risk / stale carry-over) → initialized to '' each row.
• Parameterized the sub-query (was an f-string), close the db, drop unused imports (glob/os/nska_deserialize/sqlite3/datetime) and the ArtifactHtmlReport/tsv/timeline plumbing.
• kikLocaladmin: fixed the Administartor header typo → Administrator.

Validation

• ast.parse OK; 0 legacy refs; no cross-module imports of the functions.
• Reserved-word audit clean (incl. Blob).
• pylint (CI config): 10.00/10 both.
• Each module loads in isolation: valid __artifacts_v2__, decorated, function name = key, no legacy registry.