Handle strategies which do not include DDFs and don't have Proposal Table.

[cnsetzer]

Describe the bug
In the set of v1.3 cadences, some do not have DDF fields. Additionally, there are several simulations which are restricted to only WFD. Thus when accessing the proposal table, or trying to find the PropID for the DDF key to obtain those visits, this returns a ValueError or KeyError respectively.

To Reproduce
I have used the typical method to access the summary table of these cadences, i.e.
opsimsummary.OpSimOutput.fromOpSimDB(cadence, subset='wfd',opsimversion='fbsv1p3').summary

Additional context
The following FBS v1.3 cadences raise this KeyError:
wfd_65_v1.3_10yrs.db
wfd_70_v1.3_10yrs.db
wfd_75_v1.3_10yrs.db
wfd_80_v1.3_10yrs.db
wfd_85_v1.3_10yrs.db
wfd_90_v1.3_10yrs.db
wfd_95_v1.3_10yrs.db
wfd_only_2snap_v1.3_10yrs.db
wfd_only_nomix_v1.3_10yrs.db
wfd_only_v1.3_10yrs.db
wfd_standard_v1.3_10yrs.db
wfd_65_v1.3_10yrs.db
wfd_70_v1.3_10yrs.db
wfd_75_v1.3_10yrs.db
wfd_80_v1.3_10yrs.db
wfd_85_v1.3_10yrs.db
wfd_90_v1.3_10yrs.db
wfd_95_v1.3_10yrs.db
wfd_only_2snap_v1.3_10yrs.db
wfd_only_nomix_v1.3_10yrs.db
wfd_only_v1.3_10yrs.db
wfd_standard_v1.3_10yrs.db

The following FBS v1.4 cadences raise this KeyError:
wfd_depth_scale0.65_noddf_v1.4_10yrs.db
wfd_depth_scale0.70_noddf_v1.4_10yrs.db
wfd_depth_scale0.75_noddf_v1.4_10yrs.db
wfd_depth_scale0.80_noddf_v1.4_10yrs.db
wfd_depth_scale0.85_noddf_v1.4_10yrs.db
wfd_depth_scale0.90_noddf_v1.4_10yrs.db
wfd_depth_scale0.95_noddf_v1.4_10yrs.db
wfd_depth_scale0.99_noddf_v1.4_10yrs.db

Suggested solution
I would suggest using a flag that the user must set to actively choose what to do if there is no proposal table. I.e., a flag that is no_proposal == 'all' which then uses all observations in the event that there is not a proposal table.

[rbiswas4]

Active choice is potentially possible, but probably has to be selected from a set of provided choices. There are two strategy inputs that are important:

• How do we divide (DDF and non DDF; MW ?) or not divide the outuput.
• We sample parts of the footprint, and remove both the footprint area and observations of parts that have visits less than a certain threshold over 10 years. We need to have an appropriate prescription for this.

[Catarina-Alves]

Lynne had suggested that

a useful substitute may be just modifying the sql query to be just ‘note not like “%DD%”’ — which will pull out all the visits except not DD visits

This should work well for WFD.
I guess we can talk with her to understand exactly how are the proposal tables generated and create the same number of options as the proposal tables currently have.