Use qiskit-ibm-provider api code

[kt474]

Summary

Removing as much duplication as possible from the api code

api/clients: auth.py, base.py, runtime_ws.py, version.py
api/rest: backend.py, base.py, program_job.py, root.py

Details and comments

Fixes other half of #548

[coveralls]

Pull Request Test Coverage Report for Build 5489535000

• 12 of 14 (85.71%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.5%) to 74.036%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit_ibm_runtime/runtime_job.py	0	2	0.0%

Totals
Change from base Build 5480292984:	1.5%
Covered Lines:	2401
Relevant Lines:	3243

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💛 - Coveralls

[merav-aharoni]

Overall looks fine. A few comments:

1. In qiskit_ibm_runtime/api/clients/base.py, retries==8 and in qiskit-ibm-provider/qiskit_ibm_provider/api/clients/base.py it is 5. Do you want to change it to 8 in provider?
2. There are quite a few differences between qiskit_ibm_runtime/api/rest/backend.py and qiskit-ibm-provider/qiskit_ibm_provider/api/rest/backend.py. Do we need to copy any of these to provider?
3. Same as (2) for qiskit_ibm_runtime/api/rest/program_job.py and qiskit-ibm-provider/api/rest/program_job.py
4. Same for qiskit_ibm_runtime/api/rest/root.py and qiskit-ibm-provider/api/rest/root.py. In particular, the former has a reservations method.

[kt474]

Overall looks fine. A few comments:

1. Yes, we can also increase the retries in qiskit-ibm-provider
2. We don't need to copy any of the changes in backend.py because job_limit and `reservations are no longer used
3. I believe the same applies here, we don't need to copy the changes, because the program_job.py in qiskit-ibm-provider is more up to date
4. There is no reservations endpoint in the runtime api, I don't believe it was ever used in this repo