[#54230448] Change stemcell filename format

 * Add `StemcellFilename` class
Moved pipeline publish from Pipeline to Stemcell.
Revert "Moved pipeline publish from Pipeline to Stemcell."

This reverts commit 6527566d87466130e2dfbbb497127c46e37be13a.
Revert "[#54230448] Change stemcell filename format"

This reverts commit c30091982a3d8d7106b47952643b4c9e28715f73.
Downloading a stemcell returns downloaded filename
[Finishes #54000935] Downloading vSphere stemcell for cpi lifecycle tests in rake
Begin moving stemcell logic into bosh-stemcell

AwsRegistry is seemingly an odd place to start. It's easy to move
because nothing else depends on it. It also exists solely for AWS light
stemcells.
Move vSphere systems tests out of rake and into Ruby
AWS Bat Deployment Manifest takes stemcell version, instead of object

 * internal refactor of AWS and vSphere runners
Move 'ensure teardown' logic out of rake task and into Runners
Clean up requires, move fakefs require into spec_helper

 * specs must still call 'include FakeFS::SpecHelpers' to activate fakefs
 * use full modules in specs
 * specs only require class under test
Add class to encapsulate deployments-aws repo access
Bosh::Dev::Aws::Receipts ensures the repository it needs exists
Move AwsDeploymentsRepository under Bosh::Dev::Aws and rename
Refactor Bosh::Dev::Bat::Shell

* Split up the monolithic `#run` method into more sensible logical
  blocks.
* Simplify each of those blocks.
* Add a test for the expected behavior when we ask for a tail of more
  lines than are in the output.
AwsRunner requires 'resolve'
AwsRunner requires 'resolve'

 * remove unused require 'bosh/dev/bat/shell'