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/jinja/comments.wren

@@ -0,0 +1,13 @@
+// retoor <retoor@molodetz.nl>
+
+import "jinja" for Environment, DictLoader
+
+var env = Environment.new(DictLoader.new({
+  "simple": "before{# comment #}after",
+  "multiword": "a{# this is a comment #}b",
+  "with_tags": "x{# {{ ignored }} #}y"
+}))
+
+System.print(env.getTemplate("simple").render({})) // expect: beforeafter
+System.print(env.getTemplate("multiword").render({})) // expect: ab
+System.print(env.getTemplate("with_tags").render({})) // expect: xy