Deprecation of checksum types should be done on the EasyConfig level instead of during computation

[Flamefire]

Some easyblocks, e.g. OpenCV, need to calculate md5 checksums because some build processes might require that as the filename.

Currently the deprecation warning is done in compute_checksum. I don't think it makes sense to deprecate the calculation of an e.g. MD5 checksum but only the usage in EasyConfigs.

From what I see we need to do this for:

• --inject-checksums(-to-json)
• verify_checksums() which also does auto-detection of e.g. MD5 so we can't do it at the call site.

As an enhancement I would include the offending checksum in the message as otherwise it is hard to find the issue.