LibPDF: Implement GoTo action for outline

Outline items can contain either a /Dest key or an /A key.

The /Dest key points to a "Destination" (various ways to reference a
page in the same document).

The /A key points to an "Action" which can have several types.
One type, the /GoTo type, just also points to a Destination.

Implement GoTo actions. This makes clicking "Contents" in the outline of
https://developer.apple.com/library/archive/documentation/mac/pdf/Text.pdf
work. (Almost all other items in this file's outline use /Dest.
"Contents" could too, but it uses /A /GoTo for some reason.)

(Other action types are things like opening a hyperlink, opening a
different file, playing a sound, submitting a form, etc. Actions
are also used for in-page links, not just in outlines. Many of
these action types we'll likely never want to implement.)

Userland/Libraries/LibPDF/CommonNames.h

@@ -9,6 +9,7 @@
 #include <AK/DeprecatedFlyString.h>
 
 #define ENUMERATE_COMMON_NAMES(X) \
+    X(A)                          \
     X(AIS)                        \
     X(Alternate)                  \
     X(ASCII85Decode)              \
@@ -134,6 +135,7 @@
     X(Root)                       \
     X(Rotate)                     \
     X(RunLengthDecode)            \
+    X(S)                          \
     X(SA)                         \
     X(SM)                         \
     X(SMask)                      \