fix: 🐛 Wait for serial port to be properly configured by VEXos

[ion098]

Summary:

This PR changes all serial functions to wait for VEXos to configure the smart port as generic serial.

Motivation:

VEXos takes some time to configure a smart port as generic serial, which can lead to the serial API mysteriously failing when called too soon after serial_enable.

Test Plan:

• test it compiles
• test that serial data can be sent immediately after calling serial_enable

[aghangurde]

How did you come to the 500ms figure? And what motivates specifically 5 100ms intervals?

[ion098]

re @aghangurde

How did you come to the 500ms figure? And what motivates specifically 5 100ms intervals?

According to the testing done by vexide here, generic serial generally takes 10ms to configure. I chose 500ms to provide a safety margin (The extra 490ms shouldn't matter too much since the delay should only ever happen once). Also, the code does 100 5ms intervals, not vice versa (most of the devices code that delays for some reason use 5ms as the delay time, so I used it as well).