Tests for checksums

[PVince81]

See owncloud/core#26655

Rough test plan:

• Checksum capability is returned in capabilities API

• Webdav PUT with correct checksum header: file uploaded fine

• Webdav PUT with incorrect checksum header: file upload denied with 400 Bad Request

• Webdav GET of a file on local storage: correct checksum returned in header

• Put a file directly on external storage, then Webdav GET the file through ownCloud: correct checksum returned

• Repeat the same tests with old endpoint without chunking

• Repeat the same tests with old endpoint chunking

• Repeat the same tests with new endpoint without chunking

• Repeat the same tests with new endpoint with chunking NG
  (the latter sound like a big matrix...)

@IljaN please check that this covers everything

@owncloud/qa

[PVince81]

Note: it might be enough to add the checksum header to the existing upload tests instead of adding new tests for it.

[rperezb]

@SamuAlfageme fyi

[PVince81]

@SergioBertolinSG would be good to teach developers how to write code, because you guys clearly have too much on your plate and can't write tests for everything.

Please help @IljaN write the above tests as integration tests. This can be done after his PR is merged, or as part of the PR.

[SergioBertolinSG]

Done here owncloud/core#27345