feat: change default script and predicate program generated at init

[kayagokalp]

Description

Changes default predicate to:

predicate;

fn main() -> bool {
    true
}

and default script to:

script;

use std::logging::log;

configurable {
    SECRET_NUMBER: u64 = 0
}

fn main() -> u64 {
    log(SECRET_NUMBER);
    return SECRET_NUMBER;
}

[calldelegation]

Thank you @kayagokalp 🙏!

Before the defaults were predicates returning false and script simply being empty which means you can't make any meaningful example templated testing assertions to them. These new examples are for the new templates for scripts and predicates
#5238