Adds CI to forbid some istype(src) checks.

[Contrabang]

What Does This PR Do

Adds CI to forbid some istype(src) checks that are

• Inside of an if statement
• Comparing to anything but a turf

Why It's Good For The Game

Prevents bad code from getting in the codebase (this stuff was already against our coding guidelines)

Testing

• [x] Decals didn't appear bloody when covered in blood
• [x] As a cultist, could erase runes with a dagger, except if its an open teleport portal
• [x] Could attach a guest ID to a normal ID, but not to another guest ID
• [x] Wallrechargers cannot be unanchored
• [x] Destroying mech equipment plays the correct sounds
• [x] Blood doesn't float when it shouldn't
• [x] Could light normal cigarettes with anything
• [x] Could only light fancy cigarettes (cigars and pipes) with a zippo or matches
• [x] Emagged Engi Borgs can't accidently delete their cable cuffs
• [x] Removing things from fancy storages (e.g. donut boxes) properly updates their icon
• [x] Double signs (maps, etc) can't be removed, but normal ones can.
• [x] Flipping tables works normally
• [x] All flippable tables appeared correctly
• [x] Could remove headsets from ears
• [x] Hydroponic basins (and the garden subtype) both correctly have their glow
• [x] Could put on PDAs via strip menu
• [x] Could remove PDA, handcuffs, and legcuffs via strip menu
• [x] Chaplains can still sometimes hear spooky sounds when taking a photo with a spooky cameras
• [x] /obj/item/gun/projectile/revolver/doublebarrel/improvised/cane has the right description
• [x] Burn decapitating someone doesnt delete their head/brain
• [x] Hidden pipes cant still be removed through transparent floors
• [x] Turning into a golem hasn't changed (Tested, but would appreciate confirmation!)

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Declaration

• [x] I confirm that I either do not require pre-approval for this PR, or I have obtained such approval and have included a screenshot to demonstrate this below.

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Changelog

NPFC