Add retries when running git fetch

[mazhelez]

Issue:
Builds sometimes fail with:

Error: Unexpected error when running action. Error Message: Unable to find repoVersion in AL-Go-Settings.json, StackTrace: at Get-MaxAllowedObsoleteVersion, D:\a\BCApps\BCApps\build\scripts\GuardingV2ExtensionsHelper.psm1: line 264 <- at Update-AppSourceCopVersion, D:\a\BCApps\BCApps\build\scripts\GuardingV2ExtensionsHelper.psm1: line 208 <- at Enable-BreakingChangesCheck, D:\a\BCApps\BCApps\build\scripts\GuardingV2ExtensionsHelper.psm1: line 67 <- at <ScriptBlock>, D:\a\BCApps\BCApps\build\scripts\PreCompileApp.ps1: line 63 <- at <ScriptBlock>, D:\a\BCApps\BCApps\build\projects\System Application\.AL-Go\PreCompileApp.ps1: line 7 <- at <ScriptBlock>, C:\ProgramData\BcContainerHelper\6.0.29-preview1267\BcContainerHelper\AppHandling\Run-AlPipeline.ps1: line 2070 <- at <ScriptBlock>

The underlying error is

  fatal: unable to access 'https://github.com/microsoft/BCApps/': Recv failure: Connection was aborted
  fatal: invalid object name 'origin/main'.

or sometimes

  fatal: unable to access 'https://github.com/microsoft/BCApps/': OpenSSL SSL_read: SSL_ERROR_SYSCALL, errno 0
  fatal: invalid object name 'origin/main'.

Solution:
Add retries when running git fetch to catch the instability.

Fixes AB#557642