Provide indication when loading asset entries into the list
Reviewers' note: this PR is best reviewed commit-wise.
This PR implements some strategies to provide feedback to users when the asset entry table is being refreshed. See #146 (closed) for more information. The following three stragegies are employed:
- When fetching a new asset entry list (not simply extending the existing one) the asset list fades out to be replaced with the new one. When extending the asset entry list, the existing behaviour of simply appending to the list is used.
- When fetching an asset list, a linear progress indicator is added below the asset entry table header. This provides immediate visual feedback to users that a load is happening.
- To avoid over egging the pudding w.r.t. loading indicators, the circular loading indicator at the bottom of the asset table is shown inly when extending the asset list, not when replacing it.
Closes #146 (closed)