Closes https://github.com/go-gitea/gitea/issues/30296
- Adds a DB fixture for actions artifacts
- Adds artifacts test files
- Clears artifacts test files between each run
- Note: I initially initialized the artifacts only for artifacts tests,
but because the files are small it only takes ~8ms, so I changed it to
always run in test setup for simplicity
- Fix some otherwise flaky tests by making them not depend on previous
tests
Multiple chunks are uploaded with type "block" without using
"appendBlock" and eventually out of order for bigger uploads.
8MB seems to be the chunk size
This change parses the blockList uploaded after all blocks to get the
final artifact size and order them correctly before calculating the
sha256 checksum over all blocks
Fixes#31354
