Refactor STAC -> eo3 to use odc-stac implementation

[jmettes]

At the moment STAC->eo3 is handled in here:
https://github.com/opendatacube/odc-tools/blob/develop/apps/dc_tools/odc/apps/dc_tools/_stac.py

We should use odc-stac's implementation instead:
https://github.com/opendatacube/odc-stac/blob/e7aa2e47b41ffad05b0c4a0b59f243b2709611f2/odc/stac/eo3/_eo3converter.py

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For reference, eo3->STAC is handled in eo-datasets:
https://github.com/opendatacube/eo-datasets/blob/develop/eodatasets3/stac.py
https://github.com/opendatacube/eo-datasets/blob/develop/eodatasets3/scripts/tostac.py

Would be good to have both eo3->stac and stac->eo3 directions documented somewhere