Add Sheldon Led as a FE maintainer for GitLab

Manager Justification

It's hard to specify hard requirements for becoming a maintainer, which is why the documentation consists of flexible guidelines. Reviewers are encouraged to think of their eligibility for maintainership in the terms of "I could be ready at any time to be a maintainer as long as it is justified".

• The MRs reviewed by the candidate consistently make it through maintainer review without significant additionally required changes.
• The MRs authored by the candidate consistently make it through reviewer and maintainer review without significant required changes.

Trainee Maintainer Issue: #34359 (closed).

Summary justification

• Maintainer of CustomersDot
• Working on GitLab project for 3 years (first MR - which coincidentally was a take over from Community contribution gitlab-org/gitlab!65410 (comment 821173831))
• Reviewed and approved 335+ MRs, some MRs with different aspects such as:
  • 20 were Community contribution
  • 21 with no frontend code
• Provided backend and ~test feedback, sometimes with no additional feedback from domain experts
• Coached other engineers on writing better tests and avoid rubocop:disable gitlab-org/gitlab!119942 (comment 1392631483)
• Since the Trainee Maintainer Issue was opened (2023-07-11) here's the TL;DR of the reviews:
  • Total: 93
  • No feedback: 40 (43.01%)
  • Merged as-is: 69 (74.19%)
  • No substantial additions: 5 (5.38%)
  • Maintainer's comments weren't crucial or could've been addressed in a follow up (in my opinion): 11 (11.83%)
  • Here are a few reviews that stood out as non-trivial:

MR	Summary
gitlab-org/gitlab!129936 (merged)	#34359 (comment 1662838453)
gitlab-org/gitlab!132939 (merged)	#34359 (comment 1662840103)
gitlab-org/gitlab!130789 (merged)	#34359 (comment 1662844280)
gitlab-org/gitlab!135447 (merged)	#34359 (comment 1662848393)
gitlab-org/gitlab!145340 (merged)	#34359 (comment 1909441230)
gitlab-org/gitlab!144778 (merged)	#34359 (comment 1909450002)
gitlab-org/gitlab!148844 (merged)	#34359 (comment 1909475978)

Before Merging (Manager Tasks)

• Close any relevant trainee maintainer issues with a comment indicating that this merge request is being created, as (they are no longer required to become a maintainer).
• Mention the maintainers from the given specialty and ask them to provide feedback to the manager directly.
• Leave this merge request open for 1 week, to give the maintainers time to provide feedback.
• Ensure we have at least 2 approvals from existing maintainers.

Once This MR is Merged

1. Create an access request for maintainer access to gitlab-org/gitlab
2. Join the [at]frontend-maintainers slack group
3. Ask the maintainers in your group to invite you to any maintainer-specific meeting if one exists.
4. Let a maintainer add you to gitlab-org/maintainers/frontend with Owner access level.
5. Announce it everywhere
6. Keep reviewing, start merging 🤘 😎 🤘