Radical.pilot

- merge 2122: fixed `n_nodes` for the case when `slots` are set
- merge 2123: fix 2121
- merge 2124: fixed conda-env path definition
- merge 2127: bootstrap env fix
- merge 2133, 2138: IBRun fixes
- merge 2134: agent stage_in test1
- merge 2137: agent_0 initialization fix
- merge 2142: config update
- add `deactivate` support for tasks
- add cancelation example
- added comet_mpirun to resource_xsede.json
- added test for launch method "srun"
- adding cobalt test
- consistent process counting
- preliminary FLUX support
- fix RA utilization in case of no agent nodes
- fix queue naming, prte tmp dir and process count
- fix static ve location
- fixed version discovery (srun)
- cleanup bootstrap_0.sh
- separate tacc and xsede resources
- support for Princeton's Traverse cluster
- updated IBRun tests
- updated LM IBRun


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- task overlay + docs
- iteration on srun placement
- add env support to srun
- theta config
- clean up launcher termination guard against lower level termination
errors
- cobalt rm
- optional output stager
- revive ibrun support
- switch comet FS


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- scattered fixes cfor summit


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- support for bulk callbacks
- fixed package paths for launch methods
(radical.pilot.agent.launch_method)
- updated documentation references
- raise minimum Python version to 3.6
- local submit configuration for Frontera
- switch frontera to default agent cfg
- fix cray agent config
- fix issue 2075 part 2


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- fix dependency version for radical.utils


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- code cleanup


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