Add missing textures and models from Chorus' Version

This also helps in preparing for the Nether Update (1.16). Textures were
optimised using OptiPNG by:

optipng -o7 -nx

followed by a second run with the defaults.

assets/minecraft/textures/entity/villager/profession/butcher.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "partial"
+    }
+}

assets/minecraft/textures/entity/villager/profession/farmer.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "full"
+    }
+}

assets/minecraft/textures/entity/villager/profession/fisherman.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "full"
+    }
+}

assets/minecraft/textures/entity/villager/profession/fletcher.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "full"
+    }
+}

assets/minecraft/textures/entity/villager/profession/librarian.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "full"
+    }
+}

assets/minecraft/textures/entity/villager/profession/shepherd.png.mcmeta

@@ -0,0 +1,5 @@
+{
+    "villager": {
+        "hat": "full"
+    }
+}