Fix FileCatalog cmdlets to work if -Path is not specified

[SteveL-MSFT]

Remove unnecessary check for Paths.count > 0 as there is code later to use the current working directory since -Path is not a mandatory parameter.
Updated ShouldProcess to output the internal action on adding paths rather than the user action (which is the cmdlet name).

Updated tests to not specify -Path

Fix #5594

[iSazonov]

LGTM.

[markekraus]

LGTM

[TravisEz13]

Reviewing for RC2 triage: Should process should not hardcode message string

[iSazonov]

Sorry for being late. Above we made "Including path " + tempPath.ProviderPath but here we show only path catalogFilePath - different style message.

[SteveL-MSFT]

ShouldProcess() here automatically shows the cmdlet name as the action, so it says something like: What If: Executing Test-FileCatalog against "catalogFilePath"

[iSazonov]

My question is about the difference - if an user set both Path and CatalogFilePath parameters he can get some requests for files from Path and then different style request for catalogFilePath - he can not understand that last request is for just catalog file.

[SteveL-MSFT]

If both is specified, you see this:

PS C:\Users\steve\test> New-FileCatalog -Path C:\Users\steve\test,c:\,c:\Users\steve -CatalogFilePath c:\users\steve\test\test.cat -WhatIf
What if: Including path C:\Users\steve\test
What if: Including path C:\
What if: Including path C:\Users\steve
What if: Performing the operation "New-FileCatalog" on target "c:\users\steve\test\test.cat".

[iSazonov]

Looks good. Thanks!