Added automatic mode selection

[TwoOfTwelve]

Adds an implicit mode selection. The CLI will now detect the mode based on the input files.

From the documentation of the mode flag:
By default JPlag will automatically select the mode based on your input files. If none are selected the viewer will open on the file select screen. If a single result zip is selected it will be opened in the viewer directly. Otherwise JPlag will run on the submissions in the input files and show the result in the viewer.

[TwoOfTwelve]

Adapt readme

[Kr0nox]

Blocker, as a reminder that the above comments are change requests

[Kr0nox]

Also update the documentation

JPlag/docs/1.-How-to-Use-JPlag.md

Lines 120 to 130 in 10306cc

	## Viewing Reports
	Starting with version v6.0.0, the report viewer is bundled with JPlag and will be launched automatically. The `--mode` option controls this behavior.
	By default, JPlag will process the input files and produce a zipped result file. After that, the report viewer is launched (on localhost), and the report will be shown in your browser.
	The option `--mode show` will only open the report viewer.
	This allows you to view existing reports.
	You can optionally provide the path to a report file to immediately display it in the viewer; otherwise, the viewer will require you to select a report, just like the online version.
	By specifying `--mode run`, JPlag will run but generate the zipped report but will not open the report viewer.
	An online version of the viewer is still hosted at https://jplag.github.io/JPlag/ in order to view pre-v6.0.0 reports. Your submissions will neither be uploaded to a server nor stored permanently. They are stored as long as you view them. Once you refresh the page, all information will be erased.

Inspiration may be found here #2171 or just redirect to that section

[tsaglam]

Looks good! Just a few minor things.

[sonarqubecloud]

Quality Gate passed for 'JPlag Plagiarism Detector'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
84.6% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud