gradle: add properties and modify injected-client (#1145)

* add implementation for getItemCount

* Ignore build directory in project root

* save injector results as class files

* package injected-client for shading into client

* auto-updating properties

* fix run task

* shade injected-client into jar

http-api/src/main/resources/runelite.properties

@@ -1,4 +1,4 @@
-runelite.version=${project.version}
-rs.version=${rs.version}
-runelite.commit=${git.commit.id.abbrev}
-runelite.dirty=${git.dirty}
+runelite.version=@projectver@
+rs.version=@rsver@
+runelite.commit=@gitcommit@
+runelite.dirty=@gitdirty@