[WIP] Execute mypy on opentelemetry-sdk/src

[prabhakarjuzgar]

Description

Run mypy on opentelemetry-sdk/src

Fixes # 773

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• tox -e mypy

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

• ✅login: prabhakarjuzgar / (17d43aa)
• ✅login: prabhakarjuzgar / (17d43aa, 5ff457d)
• ✅login: prabhakarjuzgar / (17d43aa, 5ff457d, 53f536e)
• ❌ The commit (5c76d9d, b2fe404, e99e464). This user is authorized, but they must confirm their affiliation with their company. Start the authorization process by clicking here, click "Corporate", select the appropriate company from the list, then confirm your affiliation on the page that appears. For further assistance with EasyCLA, please submit a support request ticket.