Basic ANT task for .NET and xPlat agent

Related Work Items: #171938
Handle options and targets correctly with xplat ant task
Updating string formats to be consistent, additional validation around Working Directory
Minor fixes
merge from master to resolve conflicts
update ant task to require path to build file, update to MIT license for all tasks
merge from master
Removed the part of PublishTasks.ps1 that generated the ReadMe.md file. It will be maintained manually.
xplat.tasks adding gradle support, and address review feedback
Maven task 1.0.0
Removing redundant Set-Location
Adding ability to create new web site during build
Removing duplicate verbose logging
Merge pull request 13941 from users/madhurig/maventask into master
Adding HelpMarkDown to Azure tasks
Fail Azure Cloud and Web tasks if more than one file to deploy is found
Version Azure tasks
helpMarkdown for many task fields