Include timestamp to output filename

[MarcoRossignoli]

Ref issue #378

Possible new option --CoverletOutputIncludetimestamp

cc: @daveMueller @petli @tonerdo

[tonerdo]

Coverlet is mostly invoked from a shell or within a build system where variables can be used. Since the filename is configurable, I don't see why we have to provide this out of the box. We can't possibly support all forms of naming conventions everyone wants.

[MarcoRossignoli]

True, I think the only useful scenario is where a dev run in local with "plain vanilla" commands like dotnet test without any vars/script.
Also looks like we don't have too much thumbs up for this feature, I think that we can close for now.

[Bertk]

The coverage result file name is not aligned with the settings for VS test. This should be improved.

Test run for C:\GitHub\coverlet\artifacts\bin\coverlet.integration.determisticbuild\debug\coverletsample.integration.determisticbuild.dll (.NETCoreApp,Version=v6.0)
Microsoft (R) Test Execution Command Line Tool Version 17.8.0-preview-23421-06 (x64)
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
Logging Vstest Diagnostics in file: C:\GitHub\coverlet\test\coverlet.integration.determisticbuild\log.txt
A total of 1 test files matched the specified pattern.
WARNING: Overwriting results file: C:\GitHub\coverlet\artifacts\tests\TestResults-net6.0-coverlet.integration.determisticbuild.trx
Results File: C:\GitHub\coverlet\artifacts\tests\TestResults-net6.0-coverlet.integration.determisticbuild.trx
Html test results file : C:\GitHub\coverlet\artifacts\tests\TestResults-net6.0-coverlet.integration.determisticbuild.html

Passed!  - Failed:     0, Passed:     1, Skipped:     0, Total:     1, Duration: < 1 ms - coverletsample.integration.determisticbuild.dll (net6.0)

Attachments:
  C:\GitHub\coverlet\artifacts\tests\f6fb2fc3-9dc0-466d-af67-f21cc7f9598f\coverage.json
  C:\GitHub\coverlet\artifacts\tests\f6fb2fc3-9dc0-466d-af67-f21cc7f9598f\coverage.cobertura.xml