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/base64/base64.wren

@@ -0,0 +1,18 @@
+import "base64" for Base64
+
+System.print(Base64.encode("Hello")) // expect: SGVsbG8=
+System.print(Base64.encode("Hello, World!")) // expect: SGVsbG8sIFdvcmxkIQ==
+System.print(Base64.encode("")) // expect:
+System.print(Base64.encode("a")) // expect: YQ==
+System.print(Base64.encode("ab")) // expect: YWI=
+System.print(Base64.encode("abc")) // expect: YWJj
+
+System.print(Base64.decode("SGVsbG8=")) // expect: Hello
+System.print(Base64.decode("SGVsbG8sIFdvcmxkIQ==")) // expect: Hello, World!
+System.print(Base64.decode("")) // expect:
+System.print(Base64.decode("YQ==")) // expect: a
+System.print(Base64.decode("YWI=")) // expect: ab
+System.print(Base64.decode("YWJj")) // expect: abc
+
+System.print(Base64.encodeUrl("Hello+World/Test")) // expect: SGVsbG8rV29ybGQvVGVzdA
+System.print(Base64.decode(Base64.encode("Test roundtrip"))) // expect: Test roundtrip