Better Bitbucket support for gitversion /output buildserver for Powershell

[arihannu]

Description

When running gitversion in Bitbucket Pipeline in Windows Powershell environment, gitversion.ps1 file is also written, in addition to the original gitversion.properties for Bash (not changed).

Related Issue

#3831

Motivation and Context

Getting the gitversion output variables into Powershell session requires now only one command:
. .\gitversion.ps1

Old way was to parse gitversion.properties file:

Get-Content .\gitversion.properties | % {$_ -replace "export ",""} | Out-File new.properties
$GitVerProps = ConvertFrom-StringData (Get-Content .\new.properties -raw)

How Has This Been Tested?

Included checks to existing tests.
I have tested this manually in our Bitbucket Pipelines and I haven't found any issues.

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[mergify]

Thank you @arihannu for your contribution!