Update issue templates (devcontainers#618)

Author: samruddhikhandale

.github/ISSUE_TEMPLATE/tracking-eol-for-images.md

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+---
+name: Tracking EOL for images
+about: Helps keep track for deprecating support for existing image variants
+title: "[Image Name] [variant/version] EOL scheduled for [date]"
+labels: image-support
+assignees: samruddhikhandale
+
+---
+
+<!-- Add a reference link (if necessary) !--->
+Depends on [add a reference link here]
+
+- [ ] Create a release (if necessary - which ensures images are up to date before deprecating )
+- [ ] Open a PR 
+- [ ] Update [templates](https://github.com/devcontainers/templates) (if necessary)
+- [ ] Update https://github.com/devcontainers/images/issues/90
+- [ ] Update [Microsoft Artifact Registry](https://mcr.microsoft.com/en-us/catalog?search=dev%20container) docs

.github/ISSUE_TEMPLATE/tracking-support-for-images.md

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+---
+name: Tracking support for images
+about: Helps keep track for adding support for new image variants
+title: Support [Image Name] [variant/version] scheduled for [date]
+labels: image-support
+assignees: samruddhikhandale
+
+---
+
+<!-- Add a reference link (if necessary) !--->
+Depends on [add a reference link here]
+
+- [ ] Open a PR 
+- [ ] Create a release
+- [ ] Update [templates](https://github.com/devcontainers/templates) (if necessary)
+- [ ] Update https://github.com/devcontainers/images/issues/90
+- [ ] Update [Microsoft Artifact Registry](https://mcr.microsoft.com/en-us/catalog?search=dev%20container) docs