Fix inconsistent donation icons and add OpenCollective (#609)

resolved #608
* fixes Inconsistent donation icons and colours #608
replaces all donation png's with svg's from https://simpleicons.org
removes svg files with "-svg" at the end

* fixes the issues due to vscode formatting the code

* fixes Discord icon
fixes some formatting errors, caused by copy& from the previous commit with wrong formatting

* fixed else-if's
added Open Collective Icon
I couldn't find the icon for the Economy Category from Feather

* added unknown_donation.svg
replaced unknown donation icon
removed old unknown.svg icon

* renamed unkown donation icon for consistency

* somehow the cmmits before didn't add the new Icon
Fixed formatting issues (again)

* fixes formatting issues (I need to look into that)

* fixed else-if's that somehow got reverted

* Fix lint

* Strict equals

* Fix lint again

assets/images/utils/unknown-donation.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-dollar-sign"><line x1="12" y1="1" x2="12" y2="23"></line><path d="M17 5H9.5a3.5 3.5 0 0 0 0 7h5a3.5 3.5 0 0 1 0 7H6"></path></svg>

assets/images/utils/unknown.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"></circle><path d="M9.09 9a3 3 0 0 1 5.83 1c0 2-3 3-3 3"></path><line x1="12" y1="17" x2="12.01" y2="17"></line></svg>