Improved styling of dashboard header buttons, download CSV button

[nielsdejong]

Small fixes to styling and improved usability through tooltips & reduced nesting

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
4 Code Smells

No Coverage information
0.0% Duplication

[codecov[bot]]

Codecov Report

Attention: 164 lines in your changes are missing coverage. Please review.

Comparison is base (a9eb6c4) 38.87% compared to head (e968118) 39.05%. Report is 12 commits behind head on develop.

Files	Patch %	Lines
src/dashboard/DashboardThunks.ts	3.75%	77 Missing :warning:
src/application/logging/LoggingThunk.ts	2.94%	33 Missing :warning:
src/dashboard/sidebar/DashboardSidebar.tsx	13.33%	12 Missing and 1 partial :warning:
src/application/ApplicationReducer.ts	40.00%	12 Missing :warning:
src/modal/ConnectionModal.tsx	46.15%	6 Missing and 1 partial :warning:
...ns/text2cypher/component/QueryTranslatorButton.tsx	0.00%	5 Missing :warning:
src/application/ApplicationThunks.ts	72.72%	3 Missing :warning:
src/application/logging/LoggingReducer.ts	85.71%	3 Missing :warning:
src/application/ApplicationSelectors.ts	66.66%	2 Missing :warning:
src/dashboard/Dashboard.tsx	50.00%	1 Missing and 1 partial :warning:
... and 4 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #729 +/- ## =========================================== + Coverage 38.87% 39.05% +0.18% =========================================== Files 204 208 +4 Lines 8546 8716 +170 Branches 2533 2597 +64 =========================================== + Hits 3322 3404 +82 - Misses 5163 5250 +87 - Partials 61 62 +1 ```

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