Update Geminabox dependency fetching with Adapter pattern

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Motivation

Due to the shutdown of the https://bundler.rubygems.org/api/v1/dependencies endpoint, we needed to update our dependency fetching approach to ensure continuous operation. It is also important that Geminabox continues to work well behind other gem proxies that don't have the same "index" feature as RubyGems.org.

Solution

This PR updates the dependency fetching process in Geminabox by introducing an adapter pattern. This new structure adds flexibility to our dependency fetching mechanism by allowing different RubyGems APIs to be used through separate adapter modules.

This update helps Geminabox handle changes in gem source services while still supporting existing systems that use different setups.

Related links:

• RubyGems.org Dependency API Deprecation.
• The New Rubygems Index Format

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@tnir May I ask you to take a look at the PR?

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@rikas @tnir Feel free to let me know if I should stop pinging you and/or should communicate in a different more efficient way (slack/discord/telegram/etc) about the "Gem-In-A-Box".