add endpoint for checking user access_token

[sblack-usu]

No description provided.

[github-actions]

✅ Result of Pytest Coverage

---------- coverage: platform linux, python 3.9.13-final-0 -----------

Name	Stmts	Miss	Cover
/dspback/init.py	0	0	100%
/dspback/config/init.py	81	0	100%
/dspback/database/init.py	0	0	100%
/dspback/database/models.py	52	0	100%
/dspback/database/procedures.py	30	3	90%
/dspback/dependencies.py	145	16	89%
/dspback/main.py	31	1	97%
/dspback/pydantic_schemas.py	136	3	98%
/dspback/routers/init.py	0	0	100%
/dspback/routers/authentication.py	65	30	54%
/dspback/routers/earthchem.py	72	44	39%
/dspback/routers/external.py	34	0	100%
/dspback/routers/hydroshare.py	69	41	41%
/dspback/routers/metadata_class.py	44	10	77%
/dspback/routers/repository_authorization.py	43	6	86%
/dspback/routers/submissions.py	27	3	89%
/dspback/routers/zenodo.py	103	72	30%
/dspback/schemas/init.py	0	0	100%
/dspback/schemas/earthchem/init.py	0	0	100%
/dspback/schemas/earthchem/model.py	206	0	100%
/dspback/schemas/external/model.py	87	0	100%
/dspback/schemas/hydroshare/model.py	113	11	90%
/dspback/schemas/zenodo/init.py	0	0	100%
/dspback/schemas/zenodo/model.py	101	0	100%
TOTAL	1439	240	83%
========================	18	passed,	1