Objectives (#2459)

* temp commit to save progress

* adds objectives

* refactors mind.addobjective a bit

* better names for my testobjectives which i'll remove later on anyways

* nullable errors

* some misc fixes

* no sorted or set, what was i thinking here?

* removes unused imports

* added commands

* fully implements stealcondition

* started uiwork

* moved prototypeicon to engine

* removes objective class & uiwork

* refactors ui to only update when opened
adds progresstexturerect

* adds some margin

* removes some testing code

* ignores objectiveprototypes on clientside

* fixes

* removes using statements for exp

* gets the job

* always show issuer

* locs & _

* giving commands some love

* Update Content.Client/GameObjects/EntitySystems/DoAfter/DoAfterBar.cs

Co-authored-by: Exp <theexp111@gmail.com>

* makes commands use new thingy

* string interpolation

* good catch exp

* loc'd

* linq gone

* runtime

* moves function from engine

* oopsie

* Update Content.Server/Objectives/Conditions/StealCondition.cs

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

* makes messages directed

* base call & validation

* shuffle once

* No? Money down!

Co-authored-by: Paul <ritter.paul1+git@googlemail.com>
Co-authored-by: Exp <theexp111@gmail.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Server/Objectives/Interfaces/IObjectiveRequirement.cs

@@ -0,0 +1,15 @@
+using Content.Server.Mobs;
+using Robust.Shared.Interfaces.Serialization;
+
+namespace Content.Server.Objectives.Interfaces
+{
+    public interface IObjectiveRequirement : IExposeData
+    {
+
+        /// <summary>
+        /// Checks whether or not the entity & its surroundings are valid to be given the objective.
+        /// </summary>
+        /// <returns>Returns true if objective can be given.</returns>
+        bool CanBeAssigned(Mind mind);
+    }
+}