Fixes 4762 - Content API for Creating, Updating, Deleting Files

[richmahn]

This is the implementation of #4762 - contents API to create, update and delete files, as well as the git/blobs API so git links in these API additions as well as the existing git/trees API work.

Dependent on go-gitea/go-sdk#152 for input/output structures. Clone that package into ./vendor/code.gitea.io/sdk of your local copy of gitea for testing and check out the richmahn:feature-4762-api-content-create-update-delete branch.

This PR makes it so BOTH the web interface and these new API routes use the same code when managing file content. Reviewing should be aware of how Create/Update/Delete worked for the web interface works. The function calls from the web routes and the api routes will first massage the input data as it can be different fore each (Example: web interface knows a file has changed in the repo since the edit was made by the last commit ID, where the API goes by the SHA of the file; or the API expects content in base64 encoding and thus must decode it where the web interface does not). Then those functions will call the file_handling module and respond with either a FileResponse (SDK) object or an error. The web & api route functions then decide how to work with the response or error accordingly.

For testing, best to check out this branch richmahn:feature-4762-api-content-create-update-delete for both the main gitea repo and the SDK package (see 2nd paragraph above). Compile and run on your local machine. Then go to your Swagger page to see the new API (starting at: http://localhost:3000/api/swagger#/repository/repoGetContents)

The new APIs are these:

• POST http://localhost:3000/api/v1/repos/{owner}/{repo}/contents/{filepath} - Create a file in a repository
• PUT http://localhost:3000/api/v1/repos/{owner}/{repo}/contents/{filepath} - Update a file in a repository
• DELETE http://localhost:3000/api/v1/repos/{owner}/{repo}/contents/{filepath} - Delete a file in a repository
• GET http://localhost:3000/api/v1/repos/{owner}/{repo}/contents/{filepath} - Gets the contents of a file or directory in a repository
• GET http://localhost:3000/api/v1/repos/{owner}/{repo}/git/blobs/{sha} - Gets the blob of a repository.

Some things to keep in mind when reviewing and testing: permissions, error messages, response data (both API and web client), and Swagger documentation - feedback welcome.

Note about the API: Even for GET calls using public repos, unlike Github, we require the user be authenticated. So even if you click on a link in the response from one call, such as a blob or tree link, you will need to make that call with authentication (token in header or in URL). For example, I use Postman in testing and I always have to set up the header information if I want to see the results.

A reminder also that most of our API doesn't have much documentation nor much detail (such as there not being a description for an API call, just each parameter). Like most all Gitea API, best to see the corresponding API docs for GitHub:

https://developer.github.com/v3/repos/contents/#get-contents
https://developer.github.com/v3/git/blobs/#get-a-blob

[techknowlogick]

@lunny changes have been made. Please review.

[lunny]

import wrong place

[richmahn]

Dang it, these things keep changing. Going to figure out how to set this in my IDE.

[lunny]

as above

[lunny]

And please resolve file conflicted. Otherwise LGTM.

conflicts resolved