Files api v2

[atonks2]

This PR starts a new /v2/files/* API to introduce enhanced functionality without any breaking changes. The first new endpoint is a new version of the Create File endpoint.

In the current implementation, switching between ASCII and EBCDIC uploads requires a code change, which means new Docker image and deployment. The new version makes better use of Content-Type and Accept headers to support the following with no code or configuration updates:

• File creation via JSON payload
• Raw file upload via multipart/form-data request bodies
  • For now the only form section supported is file, but this approach will allow for easy additions in the future
• File format conversions:
  • Send JSON, receive ASCII or EBCDIC file download
  • Send raw file, receive JSON response
  • Send ASCII, receive EBCDIC
  • Send EBCDIC, receive ASCII

[codecov-commenter]

Codecov Report

Merging #345 (2d1df49) into master (9575bfd) will increase coverage by 10.07%. The diff coverage is 73.33%.

:exclamation: Current head 2d1df49 differs from pull request most recent head 8fc9513. Consider uploading reports for the commit 8fc9513 to get more accurate results

:exclamation: Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #345 +/- ## =========================================== + Coverage 74.08% 84.15% +10.07% =========================================== Files 41 39 -2 Lines 6034 5415 -619 =========================================== + Hits 4470 4557 +87 + Misses 1291 576 -715 - Partials 273 282 +9 ```