Store symbol artifacts only for Stable builds

Only specify 5.11 so minor version will float to whatever is on AppVeyor

-fixes #3756

 * appveyor too slow

* enable TCPLinkTest
* enable FileManagerTest

* [WIP] deploy release and daily build pdbs to s3

* First pass at windows symbol generation for #2680

* Kill the conflicted compiler flag warning

* Tweaks to windows compiler flags for release builds, more qt-ish release symbols and ltcg

* Deploy tagged release symbols and CI builds to different S3 folders

* Support LTCG on iOS

* Just turn off ltcg for iOS if it is going to be such a pain

- Include appveyor YAML script in windows build other files

See also: https://github.com/appveyor/ci/issues/743

* appveyor install nsis from s3

* Pass YAML linting, pls work

* Simpler nsis download scheme