Add documentation for databricks_pipeline & make test-preview runnable

[nfx]

This pr fixes #606

[nfx]

preview

• TestPreviewAccDashboard (862.77s)
• TestPreviewAccQuery (185.40s)
• TestPreviewAccSQLEndpoint (335.28s)
• TestPreviewAccSQLEndpoints (1200.62s)
• compute/acceptance.TestPreviewAccPipelineResource_CreatePipeline (11.14s)

[alexott]

Code looks good, not clear why we get a panic in the Update function

[codecov]

Codecov Report

Merging #673 (9f58e48) into master (b3d5ec8) will decrease coverage by 0.01%.
The diff coverage is 61.53%.

@@            Coverage Diff             @@
##           master     #673      +/-   ##
==========================================
- Coverage   83.08%   83.07%   -0.02%     
==========================================
  Files          86       86              
  Lines        7912     7921       +9     
==========================================
+ Hits         6574     6580       +6     
- Misses        864      866       +2     
- Partials      474      475       +1     

Impacted Files	Coverage Δ
common/resource.go	64.70% <0.00%> (-8.63%)	⬇️
compute/resource_pipeline.go	89.01% <33.33%> (-4.10%)	⬇️
compute/resource_cluster.go	78.02% <100.00%> (ø)
compute/resource_instance_pool.go	95.69% <100.00%> (+5.79%)	⬆️
compute/resource_job.go	85.92% <100.00%> (ø)
sqlanalytics/resource_sql_endpoint.go	87.50% <100.00%> (+0.83%)	⬆️
sqlanalytics/resource_widget.go	83.45% <0.00%> (+0.75%)	⬆️

[nfx]

Code looks good, not clear why we get a panic in the Update function

@alexott , Should be fixed now. It was related to failure handling on continuous pipelines.

[nfx]

preview

• TestPreviewAccSQLEndpoints (1200.95s)
• compute/acceptance.TestPreviewAccPipelineResource_CreatePipeline (393.72s)
• sqlanalytics/acceptance.TestPreviewAccDashboard (302.75s)
• sqlanalytics/acceptance.TestPreviewAccQuery (307.88s)
• sqlanalytics/acceptance.TestPreviewAccSQLEndpoint (357.09s)