Remove useless and unused SVG elements

- Remove unused imports of xlink.
- Remove comments about which application originally wrote the text file. It's untrue because PyCharm edited it, etc.
- Remove unused IDs.
- Remove unused colours for icons rendered with RecolorImage.
- Remove useless x and y positions on 0, which is the default.
- Remove useless style setting the background to transparent.
- Remove useless whitespace in the path d attribute, and remove the then-useless XML space preserving attribute.
- Remove unused groups.
- Remove unused CSS classes.

Contributes to issue CURA-8342.

plugins/SimulationView/resources/Pause.svg

@@ -1,5 +1,4 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<svg version="1.1" id="Artwork" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
-	 viewBox="0 0 24 24" style="enable-background:new 0 0 24 24;" xml:space="preserve">
-<path style="fill:#000E1A;" d="M8,21H6V3h2V21z M18,3h-2v18h2V3z"/>
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+<path d="M8,21H6V3h2V21z M18,3h-2v18h2V3z" />
 </svg>

plugins/SimulationView/resources/Play.svg

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<svg version="1.1" id="Artwork" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
-	 viewBox="0 0 24 24" style="enable-background:new 0 0 24 24;" xml:space="preserve">
-<path style="fill:#231F20;" d="M5,20V4c0-0.8,0.9-1.3,1.5-0.9l13,8c0.6,0.4,0.6,1.3,0,1.7l-13,8C5.9,21.3,5,20.8,5,20z M7,5.8v12.4
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+<path d="M5,20V4c0-0.8,0.9-1.3,1.5-0.9l13,8c0.6,0.4,0.6,1.3,0,1.7l-13,8C5.9,21.3,5,20.8,5,20z M7,5.8v12.4
 	L17.1,12L7,5.8z"/>
 </svg>