fix: added Dockerfile and config to update yarn_gpg_key

[Akanshu-2u]

Description

Adds a custom Dev Container build to work around apt-get update failures caused by a legacy Yarn apt repository configuration.

Changes:

• Configure the devcontainer to build from a local .devcontainer/Dockerfile.
• Add a Dockerfile that removes Yarn apt source list files before running apt-get update.

Private JIRA Link:

BOMS-394

[Copilot]

Pull request overview

Adds a custom Dev Container build to work around apt-get update failures caused by a legacy Yarn apt repository configuration.

Changes:

• Configure the devcontainer to build from a local .devcontainer/Dockerfile.
• Add a Dockerfile that removes Yarn apt source list files before running apt-get update.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.devcontainer/devcontainer.json	Switches devcontainer configuration to build using a local Dockerfile.
.devcontainer/Dockerfile	Removes legacy Yarn apt repo list entries and runs apt-get update to avoid EXPKEYSIG failures.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The Dockerfile uses mcr.microsoft.com/devcontainers/universal:latest, which makes devcontainer builds non-reproducible and can introduce unexpected breakages when the upstream image updates. Consider pinning to a specific version tag (or an image digest) and updating it deliberately when needed.

Suggested change

	FROM mcr.microsoft.com/devcontainers/universal:latest
	FROM mcr.microsoft.com/devcontainers/universal:2.6.0