Updating web.config transform to handle 'location' & 'environmentvariables'

[vijayrkn]

if web.config is not present in the project & msbuild property $(EnvironmentName) with value 'Staging' is passed, then the following web.config will be generated.

• Location is added for newly generated web.configs
• Location is not added if a web.config is passed without the location.
• Environment name will be overwritten if $(EnvironmentName) is passed and existing web.config already has one.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".\WebApplication242.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout">
        <environmentVariables>
          <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Staging" />
        </environmentVariables>
      </aspNetCore>
    </system.webServer>
  </location>
</configuration>

@mlorbetske @shirhatti @pan-wang

[vijayrkn]

Partial fix for : dotnet/aspnetcore#2019

[vijayrkn]

Ping!

[natemcmaster]

Attempting to trigger PR checks.

[natemcmaster]

LGTM.