New PR template + associated CI updates #14699

Job	Run time
paths-filter	33s
Checks / Check if running codegen would produce any changes	58s
Checks / Rerun lints	32s
Checks / Lint markdown	51s
Checks / Spell Check	28s
Checks / Misc formatting	33s
Checks / markdown-paths-filter	33s
Deploy Landing Preview	0s
C++ tests	0s
Build web viewer	0s
Build rerun_js	0s
Minimum CLI Build	0s
Python Checks	0s
Rust Checks	0s
Minimum Wheel Build	0s
Upload Web	0s
Minimum Wheel Test	0s
Checks / Check links	0s
	4m 28s

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