docs: add sam2_onnx API docs, update OpenAPI spec, remove dead links

doc: update changelog, openapi specs, conf and content documentation

[refactor] move core instance segmentation (segment anything) functionality to samgis_core, bump to version 1.2.0

[docs] add CHANGELOG.md and link within sphinx docs, bump to samgis version 1.1.0

[feat] add two openapi docs builder scripts, update samgis version within docs, remove unused package.json

[docs] update docs to add openapi swagger content