Remove custom lib dependencies and replace with WPI vendordeps

[imapcgeek]

• Remove flatDir repo from build.gradle
• Remove compile directives for compile 'com.ctre.phoenix:wpiapi-java:5.12.1' and compile 'com.ctre.phoenix:api-java:5.12.1'
• Use WPI Manage Vendor Libraries command (in VS Code) to add vendor dependencies from this url ' "http://devsite.ctr-electronics.com/maven/release/com/ctre/phoenix/Phoenix-latest.json"
• Verify that the project still builds with the TalonSRX dependencies in place

[pcgeek2301]

All works and is good to go! 👍