Improve build file

[NonSwag]

Description

this is not a technical change
it only brings structure to the unorganized build.gradle.kts

summary:

• reformatted indentations
• replaced java code with kotlin where possible
• removed ugly and unnecessary line breaks
• added line breaks to clearly distinct different jobs
• removed unused repository
• shortened repository references
• use source/target compatibility instead of toolchain language version
• replaced gradle tasks with their respective references instead of using named

Checklist

• I included all information required in the sections above
• I tested my changes and approved their functionality
• I ensured my changes do not break other parts of the code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[TheMeinerLP]

LGTM