Recode database, change Maven Project to Gradle, and some stuffs

[toidicakhia]

• [x] Maven to Gradle
• [x] Change HikariCP, Custom database implemenation -> ORMLite
• [x] Folia supported (Tested in folia 1.20.4 in my friend's SMP Server)

Reason: Custom database implementation has some bugs like disconnect after execute a command, so I use ORMLite as alternative solution.

Fixed #14
Fixed #19 Fixed #11 Fixed #15