Add PR templates for atmospheric_physics

.github/PULL_REQUEST_TEMPLATE/develop-template.md

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+Originator(s):
+
+Description (include issue title and the keyword ['closes', 'fixes', 'resolves'] and issue number):
+
+List all namelist files that were added or changed:
+
+List all files eliminated and why:
+
+List all files added and what they do:
+
+List all existing files that have been modified, and describe the changes: 
+(Helpful git command: `git diff --name-status development...<your_branch_name>`)
+
+List all automated tests that failed, as well as an explanation for why they weren't fixed:
+
+Is this an answer-changing PR? If so, is it a new physics package, algorithm change, tuning change, etc?
+
+If yes to the above question, describe how this code was validated with the new/modified features:

.github/PULL_REQUEST_TEMPLATE/main-template.md

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+Tag name (The PR title should also include the tag name):
+Originator(s):
+
+List all `development` PR numbers included in this PR and the title of each:
+
+List all automated tests that failed, as well as an explanation for why they weren't fixed:

.github/pull_request_template.md

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+Please go the the `Preview` tab and select the appropriate PR template:
+
+* [development branch](?expand=1&template=develop-template.md)
+* [main branch](?expand=1&template=main-template.md)