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/variables.wren

@@ -0,0 +1,29 @@
+// retoor <retoor@molodetz.nl>
+
+import "jinja" for Environment, DictLoader
+
+var env = Environment.new(DictLoader.new({
+  "simple": "Hello {{ name }}!",
+  "escaped": "{{ html }}",
+  "safe": "{{ html|safe }}",
+  "nested": "{{ user.name }} is {{ user.age }}",
+  "subscript": "{{ items[0] }} and {{ items[1] }}",
+  "literal_str": "{{ \"literal\" }}",
+  "literal_num": "{{ 42 }}",
+  "literal_bool": "{{ true }}",
+  "literal_list": "{{ [1, 2, 3]|join(\", \") }}",
+  "default": "{{ missing|default(\"fallback\") }}",
+  "concat": "{{ a ~ b }}"
+}))
+
+System.print(env.getTemplate("simple").render({"name": "World"})) // expect: Hello World!
+System.print(env.getTemplate("escaped").render({"html": "<b>bold</b>"})) // expect: &lt;b&gt;bold&lt;/b&gt;
+System.print(env.getTemplate("safe").render({"html": "<b>bold</b>"})) // expect: <b>bold</b>
+System.print(env.getTemplate("nested").render({"user": {"name": "Alice", "age": 30}})) // expect: Alice is 30
+System.print(env.getTemplate("subscript").render({"items": ["first", "second", "third"]})) // expect: first and second
+System.print(env.getTemplate("literal_str").render({})) // expect: literal
+System.print(env.getTemplate("literal_num").render({})) // expect: 42
+System.print(env.getTemplate("literal_bool").render({})) // expect: true
+System.print(env.getTemplate("literal_list").render({})) // expect: 1, 2, 3
+System.print(env.getTemplate("default").render({})) // expect: fallback
+System.print(env.getTemplate("concat").render({"a": "Hello", "b": "World"})) // expect: HelloWorld