Ruby: trap_compression -> trap.compression

Change the trap_compression extractor option to be an object `trap` with
a nested option `compression`. This means that on the command line you
would supply the option as follows:

    codeql database create --extractor-option trap.compression=gzip

This is a little less jarring than the previous design, which would use
underscores amonst the hyphens:

    codeql database create --extractor-option trap_compression=gzip

ruby/codeql-extractor.yml

@@ -17,11 +17,15 @@ file_types:
     extensions:
       - .erb
 options:
-  trap_compression:
-    title: Controls compression for the TRAP files written by the extractor.
-    description: >
-      This option is only intended for use in debugging the extractor. Accepted
-      values are 'gzip' (the default, to write gzip-compressed TRAP) and 'none'
-      (to write uncompressed TRAP).
-    type: string
-    pattern: "^(none|gzip)$"
+  trap:
+    title: Options related to TRAP output.
+    type: object
+    properties:
+      compression:
+        title: Controls compression for the TRAP files written by the extractor.
+        description: >
+          This option is only intended for use in debugging the extractor. Accepted
+          values are 'gzip' (the default, to write gzip-compressed TRAP) and 'none'
+          (to write uncompressed TRAP).
+        type: string
+        pattern: "^(none|gzip)$"