Add ability to select which Scan Reports to use for mapping reuse

[PhilAppleby]

Add the ability to select existing scan reports for which mapping re-use is required.

Will need to be able to avoid mapping conflicts in the case of multiple available mappings

[spco]

Generally agreed this a desirable piece. Perhaps implement as-is, or as part of a wider generalisation of the mapping reuse algorithm

[AndyRae]

This is possible and straight forward for us to filter out which Scan Reports, datasets, or vocabs to reuse.

Initially start with filtering data sets. Then scan reports.