Change: move accessors to dedicated target files

[mattmundell]

What

Move target property functions out of manage_sql.c.

Why

Better file organisation. Reduces size of manage_sql.c.

References

Follows /pull/2761

Testing

Ran GET_TASKS and GET_TARGETS with main and PR. Made sure output was the same.

o m m '<get_tasks details="1" task_id="8831937d-0e87-439a-807c-a9a2cf976f6a"/>' > /tmp/task-pr
o m m '<get_tasks details="1"/>' > /tmp/tasks-pr
o m m '<get_targets details="1"/>' > /tmp/targets-pr
o m m '<get_tasks details="1" task_id="8831937d-0e87-439a-807c-a9a2cf976f6a"/>' > /tmp/task-main
o m m '<get_tasks details="1"/>' > /tmp/tasks-main
o m m '<get_targets details="1"/>' > /tmp/targets-main
diff -u /tmp/targets-main /tmp/targets-pr
diff -u /tmp/tasks-main /tmp/tasks-pr
diff -u /tmp/task-main /tmp/task-pr