SourceTask in Gradle plugin

[nulls]

What's done:

• migrated to SourceTask
• removed inputs

It closes #1026

[github-actions]

JUnit Tests (macOS, EnricoMi/publish-unit-test-result-action@v2)

2 files   -    163  2 suites   - 163   7s ⏱️ - 5m 34s
5 tests  - 1 390  5 ✔️  - 1 354  0 💤  - 36  0 ❌ ±0 
5 runs   - 2 769  5 ✔️  - 2 733  0 💤  - 36  0 ❌ ±0 

Results for commit 2f37366. ± Comparison against base commit 7b7d2b6.

This pull request removes 1390 tests.

com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check default extension properties()
com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check default reporter type value()
com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check that tasks are registered()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line for various inputs()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line has reporter type and output()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line has reporter type without output()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line in debug mode()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line in githubActions mode()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line with excludes()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line with non-existent inputs()
…

♻️ This comment has been updated with latest results.

[github-actions]

JUnit Tests (Windows, EnricoMi/publish-unit-test-result-action@v2)

2 files   -    163  2 suites   - 163   15s ⏱️ - 12m 51s
5 tests  - 1 390  5 ✔️  - 1 373  0 💤  - 17  0 ❌ ±0 
5 runs   - 2 769  5 ✔️  - 2 752  0 💤  - 17  0 ❌ ±0 

Results for commit 2f37366. ± Comparison against base commit 7b7d2b6.

This pull request removes 1390 tests.

com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check default extension properties()
com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check default reporter type value()
com.saveourtool.diktat.plugin.gradle.DiktatGradlePluginTest ‑ check that tasks are registered()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line for various inputs()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line has reporter type and output()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line has reporter type without output()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line in debug mode()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line in githubActions mode()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line with excludes()
com.saveourtool.diktat.plugin.gradle.DiktatJavaExecTaskTest ‑ check command line with non-existent inputs()
…

♻️ This comment has been updated with latest results.

[nulls]

The comment from the original is about returning back files to have a common configuration with detekt to have a common configuration for such projects.

Spotless uses FileCollection as input and it does support ant patterns, but doesn't support exclusion uses a specific methods to support ant patterns.
Need to try to use both of them...