NXCALS-7143 Bump gradle to 7.6

Update: Gradle 6.8 -> 7.6

• removed compile configuration

Maven plugin: maven -> maven-publish

• removed install task
• artifacts doesn't work

Java plugin: java -> java-library

• add api configuration

Pattern:

• compile was changed to api in api packages and implementation in service packages
• testCompile to testImplementation
• compileOnly stay untouched
• artifacts must be defined using new maven-publication syntax