Implement MySQL 8.0 native functions: format_bytes(), format_time() and ps_thread_id()

While this functions can be implemented as user SQL functions, they have become native on MySQL 8.0.16. They are simple and independent enough that backport them should be easy.
Implementing them on MariaDB would allow:

• Better compatibility with sys/performance_schema
• Nice functions to have natively in any case for formatting reasons or even as a virtual column
• Better MySQL compatibility, and avoiding user pain when migrating from MySQL from 8.0.16+
• Better performance by being C rather than user functions/SQL

https://mysql.wisborg.dk/2019/05/28/performance-schema-functions/