Add tab-completion for ALTER INDEX .. [NO] DEPENDS ON

... as added in the prior commit.

(We'd like to have tab-completion for the other object types too, but
they don't have sub-command completion yet.)

Author: Ibrar Ahmed <ibrar.ahmad@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CALtqXTcogrFEVP9uou5vFtnGsn+vHZUu9+9a0inarfYVOHScYQ@mail.gmail.com

src/bin/psql/tab-complete.c

@@ -1709,7 +1709,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER INDEX <name> */
 	else if (Matches("ALTER", "INDEX", MatchAny))
 		COMPLETE_WITH("ALTER COLUMN", "OWNER TO", "RENAME TO", "SET",
-					  "RESET", "ATTACH PARTITION");
+					  "RESET", "ATTACH PARTITION", "DEPENDS", "NO DEPENDS");
 	else if (Matches("ALTER", "INDEX", MatchAny, "ATTACH"))
 		COMPLETE_WITH("PARTITION");
 	else if (Matches("ALTER", "INDEX", MatchAny, "ATTACH", "PARTITION"))
@@ -1755,6 +1755,10 @@ psql_completion(const char *text, int start, int end)
 					  "buffering =",	/* GiST */
 					  "pages_per_range =", "autosummarize ="	/* BRIN */
 			);
+	else if (Matches("ALTER", "INDEX", MatchAny, "NO", "DEPENDS"))
+		COMPLETE_WITH("ON EXTENSION");
+	else if (Matches("ALTER", "INDEX", MatchAny, "DEPENDS"))
+		COMPLETE_WITH("ON EXTENSION");
 
 	/* ALTER LANGUAGE <name> */
 	else if (Matches("ALTER", "LANGUAGE", MatchAny))