feat: unify stac harvester and stac provider functionality

[michaelmattig]

Here is a brief summary of what I did:

[coveralls]

Coverage Report for CI Build 32950950449

Coverage decreased (-0.4%) to 87.308%

Details

• Coverage decreased (-0.4%) from the base build.
• Patch coverage: 949 uncovered changes across 10 files (2230 of 3179 lines covered, 70.15%).
• 155 coverage regressions across 5 files.

Uncovered Changes

File	Changed	Covered	%
geoengine/services/src/cli/stac_harvester/harvest.rs	1170	536	45.81%
geoengine/services/src/cli/stac_harvester/discover.rs	835	681	81.56%
geoengine/services/src/datasets/external/stac/common.rs	661	578	87.44%
geoengine/services/src/cli/stac_harvester/mod.rs	27	0	0.0%
geoengine/services/src/datasets/external/stac/loading_info.rs	183	157	85.79%
geoengine/services/src/util/retry.rs	164	148	90.24%
geoengine/services/src/datasets/external/stac/mod.rs	17	13	76.47%
geoengine/services/src/api/model/services.rs	21	18	85.71%
geoengine/services/src/bin/geoengine-cli.rs	1	0	0.0%
geoengine/services/src/cli/stac_import.rs	12	11	91.67%
Total (17 files)	3179	2230	70.15%

Coverage Regressions

155 previously-covered lines in 5 files lost coverage.

File	Lines Losing Coverage	Coverage
geoengine/services/src/datasets/external/edr.rs	146	76.38%
geoengine/services/src/datasets/external/stac/loading_info.rs	3	86.63%
geoengine/operators/src/cache/shared_cache.rs	2	85.03%
geoengine/services/src/datasets/external/stac/mod.rs	2	81.43%
geoengine/services/src/quota/mod.rs	2	94.55%

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Coverage Stats

Relevant Lines:	145635
Covered Lines:	127151
Line Coverage:	87.31%
Coverage Strength:	481237.27 hits per line

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💛 - Coveralls