Simplify GitHub issue template

[GitHub] Prevent confirmed issues from being marked as stale

[Resolver] Sort external source dependencies first

fix dead link

This resolves a (potential) ordering bug due to pre-releases.

In #possibility_versions_for_root_name, we check whether dependencies on a pod are pre-release or external source, and if so allow pre-releases. It is crucial, therefore, that any external source dependencies have been addressed before any transitive source without the external source, so that pre-releases are (properly) allowed.

 [Resolver] Fix multi-source resolution

Do not include test spec resource and framework paths of external targets into scripts

Show warning when Pod source uses unencrypted HTTP

Restore `development_pod_targets` public method in installer

Fix build

Set development pods' podspecs syntax to Ruby when appropriate

Fix duplicate framework/resource output paths caused by the same output file name

Fix duplicate framework and resource output paths caused by the same output name but different source for each configuration

Allow installation of a pod with its own Swift version on multiple targets

Show warning when SDK provider tries to push a version with an unencrypted HTTP source

Add information about how to run tests

This is something that took me a few minutes to find, so let's make it easier for new people to know how to run a specific test, as that's very commonly used when preparing a PR. 

As there is a lot of potential small changes in this PR, please feel free to directly apply any changes and merge from there.