ConceptSchemeSelection: Computed properties cost too much and are updated way too often

[stefandesu]

While further improving Cocoda's performance, I have noticed that the application spends a lot of computing time with updating computed properties in the ConceptSchemeSelection component. Specifically, these four computed properties take a lot of computing time:

• filteredSchemes
• registryFilterOptions
• languageFilterOptions
• typeFilterOptions

All of these filter and iterate over all schemes and are updated every time there is ANY change on a scheme, which apparently happens extremely often, even during concept updates.

To mitigate this, it might be possible to use watchers instead and compute these properties in debounced methods. They can/should also be optimized in other ways as well.