Update Issue and PR templates

[sdzhepa]

Description (*)

This PR contains 2 improvements/updates

1. Updated Issue related templates

Added section that allows a reporter to set initial Severity during issue reporting as it described on DevDoc Who and how can define severity and priority

Issue reporters can provide their own evaluation for severity by selecting a checkbox in the Issue description.

2. Improve Pull Request templates

Added keyword to the section Fixed Issue

Fixes magento/magento2#<issue_number>

This keyword should improve automatically linking PR -> Issue, according to GitHub documentation Linking a pull request to an issue using a keyword

[m2-assistant]

Hi @sdzhepa. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento give me test instance - deploy test instance based on PR changes
• @magento give me 2.4-develop instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Guide documentation.

[sdzhepa]

@magento run all tests

[ihor-sviziev]

Approved ✔
Test failures are definitely not related to changes in this PR.

[magento-engcom-team]

Hi @ihor-sviziev, thank you for the review.
ENGCOM-7537 has been created to process this Pull Request

[magento-engcom-team]

Hi @okorshenko, thank you for the review.
ENGCOM-7537 has been created to process this Pull Request

[engcom-Alfa]

QA not applicable

[engcom-Charlie]

Failed functional tests not related to changes from this PR.

[m2-assistant]

Hi @sdzhepa, thank you for your contribution!
Please, complete Contribution Survey, it will take less than a minute.
Your feedback will help us to improve contribution process.