feat: add cJSON and SQLite amalgamation source files under deps/

Add the cJSON library (cJSON.c, cJSON.h) and SQLite amalgamation
(sqlite3.c, sqlite3.h, sqlite3ext.h, shell.c) as vendored dependencies
in the deps/ directory for use by the project build system.

test/dns/dns.wren

@@ -0,0 +1,8 @@
+import "dns" for Dns
+
+var addresses = Dns.lookup("localhost")
+System.print(addresses is List) // expect: true
+System.print(addresses.count > 0) // expect: true
+
+var first = addresses[0]
+System.print(first == "127.0.0.1" || first == "::1") // expect: true