Replacing existing browser tree node png icons with the svg icons. Made

it compatible with the pgAdmin 4 color combination.

TODO::
Icons for the following nodes are in PNG format.
- Domain Constraint (Only the invalid icon)
- pgAgent Job Steps
- Green Plum database server
- Server (Only server.png, which is used in the create/edit dialog)

web/pgadmin/browser/server_groups/servers/databases/extensions/static/img/coll-extension.svg

@@ -0,0 +1 @@
+<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><defs><style>.cls-1,.cls-4{fill:#def4fd;}.cls-2{fill:#717f8e;}.cls-3{fill:none;stroke:#717f8e;}.cls-3,.cls-4{stroke-linejoin:round;stroke-width:0.75px;}.cls-4{stroke:#2980b9;stroke-linecap:round;}</style></defs><title>coll-extension</title><path class="cls-1" d="M3,12.11a.62.62,0,0,1-.62-.62v-8A.62.62,0,0,1,3,2.86H8.65a.62.62,0,0,1,.62.61V9.14l-3,3Z"/><path class="cls-2" d="M8.65,3.23a.24.24,0,0,1,.24.24V9L6.14,11.73H3a.24.24,0,0,1-.24-.24v-8A.24.24,0,0,1,3,3.23H8.65m0-.75H3a1,1,0,0,0-1,1v8a1,1,0,0,0,1,1H6.45L9.64,9.29V3.47a1,1,0,0,0-1-1Z"/><polyline class="cls-3" points="9.42 8.5 5.9 8.52 5.9 12.48"/><rect class="cls-4" x="0.19" y="5.12" width="6.01" height="2.01"/><path class="cls-1" d="M5,14.11a.62.62,0,0,1-.62-.62v-8A.62.62,0,0,1,5,4.86h5.61a.62.62,0,0,1,.62.61v5.66l-3,3Z"/><path class="cls-2" d="M10.65,5.23a.24.24,0,0,1,.24.24V11L8.14,13.73H5a.24.24,0,0,1-.24-.24v-8A.24.24,0,0,1,5,5.23h5.61m0-.75H5a1,1,0,0,0-1,1v8a1,1,0,0,0,1,1H8.45l3.19-3.19V5.47a1,1,0,0,0-1-1Z"/><polyline class="cls-3" points="11.42 10.5 7.9 10.52 7.9 14.48"/><rect class="cls-4" x="2.19" y="7.12" width="6.01" height="2.01"/></svg>

web/pgadmin/browser/server_groups/servers/databases/extensions/static/img/extension.svg

@@ -0,0 +1 @@
+<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><defs><style>.cls-1,.cls-4{fill:#def4fd;}.cls-2{fill:#717f8e;}.cls-3{fill:none;stroke:#717f8e;}.cls-3,.cls-4{stroke-linejoin:round;stroke-width:0.75px;}.cls-4{stroke:#2980b9;stroke-linecap:round;}</style></defs><title>extension</title><path class="cls-1" d="M3,13.11a.62.62,0,0,1-.62-.62v-9A.62.62,0,0,1,3,2.86H9.65a.62.62,0,0,1,.62.62v6.66l-3,3Z"/><path class="cls-2" d="M9.65,3.23a.24.24,0,0,1,.24.24V10L7.14,12.73H3a.24.24,0,0,1-.24-.24v-9A.24.24,0,0,1,3,3.23H9.65m0-.75H3a1,1,0,0,0-1,1v9a1,1,0,0,0,1,1H7.45l3.19-3.19V3.47a1,1,0,0,0-1-1Z"/><polyline class="cls-3" points="10.42 9.5 6.9 9.52 6.9 13.48"/><rect class="cls-4" x="0.19" y="5.12" width="6.01" height="2.01"/></svg>