Updated arguments for `diktat-cli`

[nulls]

What's done:

• reporter is optional now
• output is required now when reporter is provided
• renamed parameters are related to plain output
• added a new type PLAIN_GROUP_BY_FILE

It closes #1793

[codecov[bot]]

Codecov Report

Attention: 75 lines in your changes are missing coverage. Please review.

Comparison is base (02c1a7c) 78.55% compared to head (0029cee) 78.40%. Report is 1 commits behind head on master.

Files	Patch %	Lines
...lin/com/saveourtool/diktat/cli/DiktatProperties.kt	0.00%	61 Missing :warning:
...ourtool/diktat/ktlint/DiktatReporterFactoryImpl.kt	0.00%	9 Missing :warning:
.../diktat/ruleset/rules/chapter2/kdoc/KdocMethods.kt	73.68%	0 Missing and 5 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1860 +/- ## ============================================ - Coverage 78.55% 78.40% -0.15% - Complexity 2456 2463 +7 ============================================ Files 133 133 Lines 8654 8688 +34 Branches 2189 2200 +11 ============================================ + Hits 6798 6812 +14 - Misses 882 897 +15 - Partials 974 979 +5 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[github-actions[bot]]

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

   164 files  ±0     164 suites  ±0   11m 43s :stopwatch: + 4m 56s 1 423 tests ±0  1 386 :heavy_check_mark: ±0  37 :zzz: ±0  0 :x: ±0  2 802 runs  ±0  2 765 :heavy_check_mark: ±0  37 :zzz: ±0  0 :x: ±0 

Results for commit 0029cee6. ± Comparison against base commit d14f27da.

:recycle: This comment has been updated with latest results.

[github-actions[bot]]

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

   164 files  ±0     164 suites  ±0   7m 25s :stopwatch: +11s 1 423 tests ±0  1 406 :heavy_check_mark: ±0  17 :zzz: ±0  0 :x: ±0  2 802 runs  ±0  2 785 :heavy_check_mark: ±0  17 :zzz: ±0  0 :x: ±0 

Results for commit 0029cee6. ± Comparison against base commit d14f27da.

:recycle: This comment has been updated with latest results.