Ties research servers to Techwebs and de-hardcodes research point gen (#72513)

## About The Pull Request

Research point generation is now done on all techwebs that have
``should_generate_points`` set to TRUE, which by default is only the
Science techweb.

I also entirely replaced the old 'servers' and 'master_servers' lists on
SSresearch with the individual 'techweb_servers' (that already existed
prior to this PR, the title is a little misleading) which are all stored
on the individual techwebs, so we no longer store these in 2-3 different
lists. Funnily enough, master server's list was unused as their behavior
was refactored a good while ago.

Sabotaging a master server now only affects the techweb the master
server is connected to, rather than cut everyone's by half

I also removed ``calculate_server_coefficient`` instead of reworked it
to work with techweb servers, because it was entirely unused.

## Why It's Good For The Game

Better consistency for several techwebs, as sabotaging one techweb won't
sabotage all of them.
This was also at the request of one of our contributors who wanted to
make use of this system but didn't know that non-science techwebs didn't
generate points, so here you go.

## Changelog

🆑
fix: If there are several techwebs, sabotaging the master server of one
of them will no longer cut research point generation of the rest.
/🆑

code/modules/research/techweb/_techweb.dm

@@ -48,6 +48,13 @@
 	///All research servers connected to this individual techweb.
 	var/list/obj/machinery/rnd/server/techweb_servers = list()
 
+	///Boolean on whether the techweb should generate research points overtime.
+	var/should_generate_points = FALSE
+	///A multiplier applied to all research gain, cut in half if the Master server was sabotaged.
+	var/income_modifier = 1
+	///The amount of research points generated the techweb generated the latest time it generated.
+	var/last_income
+
 	/**
 	 * Assoc list of relationships with various partners
 	 * scientific_cooperation[partner_typepath] = relationship