fix: Create CODEOWNERS and update template

[Atanda1]

Description

This pull request includes updates to the code ownership and pull request template files. The changes aim to clarify the default reviewers for the repository and improve the pull request submission process.

Updates to code ownership:

• Added default code owners for the entire repository in the .github/CODEOWNERS file. ([.github/CODEOWNERSR1-R5](https://github.com/paycrest/contracts/pull/58/files#diff-3d36a1bf06148bc6ba1ce2ed3d19de32ea708d955fed212c0d27c536f0bd4da7R1-R5))

Improvements to pull request template:

• Removed the code of conduct and contribution guidelines notice from the beginning of the .github/PULL_REQUEST_TEMPLATE.md file. ([.github/PULL_REQUEST_TEMPLATE.mdL1-L2](https://github.com/paycrest/contracts/pull/58/files#diff-18813c86948efc57e661623d7ba48ff94325c9b5421ec9177f724922dd553a35L1-L2))
• Updated the references section to include an example of related pull requests/issues from other repositories. ([.github/PULL_REQUEST_TEMPLATE.mdL17-R15](https://github.com/paycrest/contracts/pull/58/files#diff-18813c86948efc57e661623d7ba48ff94325c9b5421ec9177f724922dd553a35L17-R15))
• Re-added the code of conduct and contribution guidelines notice to the end of the .github/PULL_REQUEST_TEMPLATE.md file. ([.github/PULL_REQUEST_TEMPLATE.mdR34-R36](https://github.com/paycrest/contracts/pull/58/files#diff-18813c86948efc57e661623d7ba48ff94325c9b5421ec9177f724922dd553a35R34-R36))

References

.github/CODEOWNERS
.github/PULL_REQUEST_TEMPLATE.md

Checklist

• I have added documentation for new/changed functionality in this PR
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not master