Start implementation of database functionality, starting with table generation.

This database will be stored in the user's XDG_DATA_HOME directory under a folder called `com.github.joshstrobl.koto`.

Refactored Koto Track Listing into a dedicated Disc View component, break apart out CDs / Discs into relevant Disc View components, sorting them by the disc and showing a label if there are more than one discs / CDs.

Started using the row-activated event for our Artist GtkListBox instead of having press events on the artist buttons. Makes switching between artists far more reliable. Added a slide left / right stack animation and set its animation to 400ms so it's in the goldilocks zone (IMO) of not being too fast or too slow.

Fix a warning related to scale factor fetching in the PlayerBar.

theme/_disc-view.scss

@@ -0,0 +1,20 @@
+@import "vars";
+
+.disc-view {
+	& > box { // Horizontal box with image and disc labe
+		color: #ccc;
+		margin: 10px 0;
+	}
+
+	& .track-list {
+		& > row {
+			&:nth-child(odd):not(:hover) {
+				background-color: $midnight;
+			}
+
+			&:nth-child(even), &:hover {
+				background-color: $grey;
+			}
+		}
+	}
+}