Description of problem:
`pcs resource create` fails with a traceback if empty interval is specified for an operation

Version-Release number of selected component (if applicable):
pcs-0.11.4-6

How reproducible:
always, easily

Steps to Reproduce:
1. pcs resource create test ocf:pacemaker:Dummy op monitor interval=

Actual results:
Traceback (most recent call last):
File "/usr/sbin/pcs", line 33, in <module>
sys.exit(load_entry_point('pcs==0.11.4', 'console_scripts', 'pcs')())
File "/usr/lib/python3.9/site-packages/pcs/app.py", line 273, in main
routing.create_router(cmd_map, [])(
File "/usr/lib/python3.9/site-packages/pcs/cli/common/routing.py", line 33, in _router
return cmd_map[sub_cmd](lib, argv_next, modifiers)
File "/usr/lib/python3.9/site-packages/pcs/cli/common/routing.py", line 33, in _router
return cmd_map[sub_cmd](lib, argv_next, modifiers)
File "/usr/lib/python3.9/site-packages/pcs/resource.py", line 745, in resource_create
lib.resource.create(
File "/usr/lib/python3.9/site-packages/pcs/cli/common/lib_wrapper.py", line 95, in decorated_run
return run_with_middleware(run, cli_env, *args, **kwargs)
File "/usr/lib/python3.9/site-packages/pcs/cli/common/middleware.py", line 14, in run
return next_in_line(env, *args, **kwargs)
File "/usr/lib/python3.9/site-packages/pcs/cli/common/middleware.py", line 42, in apply
result_of_next = next_in_line(env, *args, **kwargs)
File "/usr/lib/python3.9/site-packages/pcs/cli/common/middleware.py", line 80, in apply
result_of_next = next_in_line(env, *args, **kwargs)
File "/usr/lib/python3.9/site-packages/pcs/cli/common/lib_wrapper.py", line 86, in run
lib_call_result = run_library_command(lib_env, *args, **kwargs)
File "/usr/lib/python3.9/site-packages/pcs/lib/commands/resource.py", line 433, in create
primitive_element = resource.primitive.create(
File "/usr/lib/python3.9/site-packages/pcs/lib/cib/resource/primitive.py", line 232, in create
return append_new(
File "/usr/lib/python3.9/site-packages/pcs/lib/cib/resource/primitive.py", line 290, in append_new
create_operations(
File "/usr/lib/python3.9/site-packages/pcs/lib/cib/resource/operations.py", line 398, in create_operations
append_new_operation(operations_element, id_provider, operation)
File "/usr/lib/python3.9/site-packages/pcs/lib/cib/resource/operations.py", line 428, in append_new_operation
options["interval"],
KeyError: 'interval'

Expected results:
No traceback, print a nice error message.

Additional info:
It works with an empty timeout:

1. pcs resource create test ocf:pacemaker:Dummy op monitor timeout=
2. pcs resource config test
   Resource: test (class=ocf provider=pacemaker type=Dummy)
   Operations:
   migrate_from: test-migrate_from-interval-0s
   interval=0s
   timeout=20s
   migrate_to: test-migrate_to-interval-0s
   interval=0s
   timeout=20s
   monitor: test-monitor-interval-60s
   interval=60s
   reload: test-reload-interval-0s
   interval=0s
   timeout=20s
   reload-agent: test-reload-agent-interval-0s
   interval=0s
   timeout=20s
   start: test-start-interval-0s
   interval=0s
   timeout=20s
   stop: test-stop-interval-0s
   interval=0s
   timeout=20s