Tests tests tests

- tests for #Copy
- added a “disable” helper to disable specific tests instead of just commenting them out
- “disable” will print out warnings about disabled tests (hopefully with links to corresponding issues)
- cleanup bug repro that has been subsumed into tests

Signed-off-by: dubo-dubon-duponey <dubodubonduponey+github@pm.me>

examples/tests/copy/invalid/cache/main.cue

@@ -0,0 +1,49 @@
+package testing
+
+test1: {
+	string
+
+	#dagger: {
+		compute: [
+			{
+				do: "fetch-container"
+				ref: "busybox"
+			},
+			{
+				do: "copy"
+				from: [{do: "fetch-container", ref: "alpine"}]
+				src: "/etc/issue"
+				dest: "/"
+			},
+			{
+				do: "export"
+				source: "/issue"
+				format: "string"
+			},
+		]
+	}
+}
+
+test2: {
+	string
+
+	#dagger: {
+		compute: [
+			{
+				do: "fetch-container"
+				ref: "busybox"
+			},
+			{
+				do: "copy"
+				from: [{do: "fetch-container", ref: "busybox"}]
+				src: "/etc/issue"
+				dest: "/"
+			},
+			{
+				do: "export"
+				source: "/issue"
+				format: "string"
+			},
+		]
+	}
+}