Add isolated gen-level photons to the nanoaod

[AndrewLevin]

PR description:

I have added a collection of isolated gen photons to the Rivet particle level producer in CMSSW (cms-sw#28371), and I want to also add it to the NANOAODSIM. This is useful for reporting cross sections with photons in the final state.

PR validation:

I have run over a recent ttbar relval sample and found that this pull request increases the size of the nanoaod by around 0.025%.

[gpetruc-bot]

Automatic test started, see https://gitlab.cern.ch/cms-nanoAOD/nanoAOD-integration/pipelines/1332995/builds

[gpetruc-bot]

Automatic test report for 1332995

• gitlab pipeline at https://gitlab.cern.ch/cms-nanoAOD/nanoAOD-integration/pipelines/1332995/builds
• outputs at https://cms-nanoaod-integration.web.cern.ch/integration/test_pr_449/

Code integration

Code checks passed for this PR

Code format passed for this PR

Tests

• Long test data102X (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test data106Xul17 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test data106Xul18 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test data80X (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test data94X (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test data94X2016 (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test data94Xv2 (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc102X (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc106Xul16 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc106Xul17 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc106Xul18 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc80X (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc94X (10000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc94X2016 (9000 events): passed, no significant changes; dqm plots: all, diff
• Long test mc94Xv2 (9000 events): passed, no significant changes; dqm plots: all, diff
• Test mc_94Xv2: passed
• Test mc_102X: passed
• Test data_94X: passed
• Test data_102X: passed

Disk size report

Sample	kb/event	ref kb/event	diff
TTbar MC 102X	1.925	1.923	0.001 ( +0.1% )
TTbar MC 94Xv1	1.989	1.988	0.001 ( +0.1% )
TTbar MC 94Xv2	2.026	2.023	0.002 ( +0.1% )
TTbar MC 94X2016	1.810	1.810	0.000 ( +0.0% )
TTbar MC 80X	1.941	1.939	0.002 ( +0.1% )
Data 102X	1.011	1.011	0.000 ( +0.0% )
Data 94Xv1	0.971	0.971	0.000 ( +0.0% )
Data 80X	0.813	0.814	-0.000 ( -0.0% )