Reworks and adds a few flags (the fabric kind)

[DisturbHerb]

[MAPPING][OBJECTS][FEATURE][REWORK]

About the PR

This PR re-organises obj/decal/wallsign/flag into its own type, obj/decal/poster/flag, and introduces a new obj/item/flag that can be placed on walls much like fabric banners (#5036). Flags can also now be taken down from walls by attacking them with a free hand. All instances of flags in the public repository have been updated with the new file path. I hope.

Also, more flags. Thanks to Geonightman#2706 on Discord for making the icons for these.*

*this has been updated like numerous times sorry (accurate as of 1 feb 2023)

I drew the folded flag states and the blank flag stuff and I don't love them, feedback will be appreciated.

All of the flags, save for the lesbian pride ones, are currently player-unobtainable.

Why's this needed?

Flags are nice and I wanted them for a thing.

(u)DisturbHerb + Geonightman
(+)Flags can now be hung up and removed from walls.
(+)Adds a bunch of pride flags.

[ZeWaka]

Why not just have a generic flag that can be painted like a canvas?

[DisturbHerb]

Why not just have a generic flag that can be painted like a canvas?

we've already got banners tho

i should add: the main reason why i'm implementing flags as their own thing as opposed to just BEEFing up banner code is primarily for mapping and so we could have a fun pre-made asset to decorate things with. i suspect the confusion might be brought about due to the inclusion of the blank flag, so i'd be perfectly happy to just turn that into an abstract type and killing it all together*

*i forgot that white flags have actual meaning, woops, we could put some more thought into it

[github-actions]

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[DisturbHerb]

Opening this PR as-is for review (since this was never actually opened).

[TobleroneSwordfish]

seems cool