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/datetime/datetime.wren

@@ -0,0 +1,28 @@
+import "datetime" for DateTime, Duration
+
+var now = DateTime.now()
+System.print(now.year >= 2024) // expect: true
+System.print(now.month >= 1 && now.month <= 12) // expect: true
+System.print(now.day >= 1 && now.day <= 31) // expect: true
+System.print(now.hour >= 0 && now.hour <= 23) // expect: true
+System.print(now.minute >= 0 && now.minute <= 59) // expect: true
+System.print(now.second >= 0 && now.second <= 59) // expect: true
+
+var ts = DateTime.fromTimestamp(0)
+System.print(ts.year) // expect: 1970
+
+var d1 = Duration.fromSeconds(60)
+System.print(d1.seconds) // expect: 60
+System.print(d1.minutes) // expect: 1
+
+var d2 = Duration.fromMinutes(2)
+System.print(d2.seconds) // expect: 120
+
+var d3 = Duration.fromHours(1)
+System.print(d3.minutes) // expect: 60
+
+var d4 = Duration.fromDays(1)
+System.print(d4.hours) // expect: 24
+
+var sum = d1 + d2
+System.print(sum.seconds) // expect: 180