WIP: Exporter: initial support for some Unity Catalog resources

[alexott]

Changes

Initial support for exporting of the following resources:

• databricks_catalog
• databricks_schema
• databricks_volume
• databricks_connection
• databricks_grants
• databricks_share
• databricks_recipient
• databricks_registered_model
• databricks_metastore
• databricks_metastore_assignment

Code may emit unsupported resources - support for them will be in the subsequent PRs. ~Grants support depends on the fix for #3245.~ Requires #3247 to correctly resolve references to schemas, etc.

Also, includes a bit of refactoring of the repeatable code for emitting in the incremental mode.

Tests will be added separately when we get support for more resources, such as grants, etc.

Tests

• [x] make test run locally
• [x] relevant change in docs/ folder
• [ ] covered with integration tests in internal/acceptance
• [ ] relevant acceptance tests are passing
• [ ] using Go SDK

[codecov-commenter]

Codecov Report

Attention: 74 lines in your changes are missing coverage. Please review.

Comparison is base (6ae2baf) 83.60% compared to head (7e22fb5) 83.74%. Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3242      +/-   ##
==========================================
+ Coverage   83.60%   83.74%   +0.13%     
==========================================
  Files         173      173              
  Lines       15477    15750     +273     
==========================================
+ Hits        12940    13190     +250     
- Misses       1773     1787      +14     
- Partials      764      773       +9     

Files	Coverage Δ
exporter/model.go	83.96% <100.00%> (+0.50%)	:arrow_up:
exporter/context.go	82.72% <85.84%> (+0.07%)	:arrow_up:
exporter/util.go	77.82% <21.73%> (-1.89%)	:arrow_down:
exporter/importables.go	79.47% <86.51%> (+2.96%)	:arrow_up: