Superset: Improvements following user testing

[e-belfer]

Following the first round of user testing, we should make some key improvements to Superset in preparation for a second round of asynchronous user tests. This includes issues descoped in #3867 and any key improvements identified in user tests that must be fixed prior to a public beta launch.

Critical Infrastructure Problems

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1. Figure out permissions problems with auto-complete and samples
2. Debug auth0 problems with Github

Documentation Gaps

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1. Document annotation layers
2. Document filtering using LIKE and ILIKE - why doesn't this work as expected?
3. Document: changing the name of the series on the legend
4. Add a note on citing PUDL

Infrastructure Gaps

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1. Get rid of the bar for numeric fields in table charts
2. Figure out if we can spruce up the auth0 text
3. Customize the home page - e.g., https://medium.com/towards-data-engineering/customize-apache-superset-home-page-to-fit-any-html-block-85f8d4b58419. Alternatively, figure out how redirect or emphasize the welcome dashboard.

Problems to investigate

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1. Chart titles - see Configuring chart title, image size and resolution, and file name on export apache/superset#30619
2. Chart export options - pick DPI and custom width and length? - see Configuring chart title, image size and resolution, and file name on export apache/superset#30619
3. Change chart names on export - see Configuring chart title, image size and resolution, and file name on export apache/superset#30619
4. User permissions (as discussed in Make superset dashboard improvements for user testing #3867)
5. Change CSV/Excel names on export - see fix(excel/csv filename on chart download): downloads zip file and excel/csv file with chart name. apache/superset#27409
6. Can save permissions be turned off by default? Would the button still show up? - can publish on Superset might be an option to toggle here