feat: rename IO.write to IO.print and add Unicode escape support in strings

Rename the IO.write method to IO.print, which now prints without a trailing newline, and add a new IO.print method that appends a newline after output. Update all benchmark, example, and test files to use IO.print instead of IO.write. Additionally, implement Unicode escape sequence parsing in the compiler's string tokenizer, supporting \uXXXX and \u{...} syntax with proper UTF-8 encoding for code points up to U+10FFFF.

test/if.wren

@@ -1,28 +1,28 @@
 // Evaluate the 'then' expression if the condition is true.
-if (true) IO.write("good") // expect: good
-if (false) IO.write("bad")
+if (true) IO.print("good") // expect: good
+if (false) IO.print("bad")
 
 // Evaluate the 'else' expression if the condition is false.
-if (true) IO.write("good") else IO.write("bad") // expect: good
-if (false) IO.write("bad") else IO.write("good") // expect: good
+if (true) IO.print("good") else IO.print("bad") // expect: good
+if (false) IO.print("bad") else IO.print("good") // expect: good
 
 // Allow blocks for branches.
-if (true) { IO.write("block") } // expect: block
-if (false) null else { IO.write("block") } // expect: block
+if (true) { IO.print("block") } // expect: block
+if (false) null else { IO.print("block") } // expect: block
 
 // Assignment in if condition.
 var a = false
-if (a = true) IO.write(a) // expect: true
+if (a = true) IO.print(a) // expect: true
 
 // Newline after "if".
 if
-(true) IO.write("good") // expect: good
+(true) IO.print("good") // expect: good
 
 // Newline after "else".
-if (false) IO.write("bad") else
-IO.write("good") // expect: good
+if (false) IO.print("bad") else
+IO.print("good") // expect: good
 
 // Only false is falsy.
-if (0) IO.write(0) // expect: 0
-if (null) IO.write(null) // expect: null
-if ("") IO.write("empty") // expect: empty
+if (0) IO.print(0) // expect: 0
+if (null) IO.print(null) // expect: null
+if ("") IO.print("empty") // expect: empty