Add release calendar to releases page

Why is this change being made?

Add a releases calendar to the GitLab releases page. This list was built based on the information provided by the releases.yml file (introduced on !127839 (merged))

Implementation details:

• Adds a new generator to fetch the data from releases.yml
• Configure the proxy to use the information from the generator.
• Adds a new table on the Releases page to display the upcoming release information.

Related to #34176 (closed)

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
  • The when to get approval handbook section explains the workflow in more detail
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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