Add PR template and CODEOWNERS file

- Add pull request template with checklist
- Add CODEOWNERS file assigning @softservedata as code owner

Author: 1g0s

.github/CODEOWNERS

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+# CODEOWNERS file
+# This file defines code ownership for the repository
+# Reference: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
+
+# All files in the main branch are owned by softservedata
+* @softservedata

.github/pull_request_template.md

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+## Describe your changes
+
+## Issue ticket number and link
+
+## Checklist before requesting a review
+- [ ] I have performed a self-review of my code
+- [ ] If it is a core feature, I have added thorough tests
+- [ ] Do we need to implement analytics?
+- [ ] Will this be part of a product update? If yes, please write one phrase about this update