closes #3554

Changes:

• fixed Dockerfile FromAsCasing warnings: 'as' and 'FROM' keywords' casing do not match
• fixed Fockerfile LegacyKeyValueFormat warnings: "ENV key=value" should be used instead of legacy "ENV key value" format
• exposed image RepoDigests in the image details view

Screenshots:

• image with no digest
  

• image with digest
  

Notes

• if the image has no digest, the row is hidden
• since an image may have more than one digest, the right column is itself a table. Currently this is true even if there's only one digest. We could change this, so that if there's only one digest in the array, a normal row will be shown with Digest key on the left and the digest value on the right, and only show Digests with a table on the right when there are more than one digests. This would, however, mean almost duplicating the row html code.
• I made the digests table datatable class, which removes the bottom margine, which is simmilar to the environmental variables table which also has that class. However, the labels table doesn't have this class and thus has a bottom margin of 20px, is this intentional, or was the datatable class missed for that?

PS. Force push was to amend the issue reference in the commit message (changed from discussion reference #9595 to issue reference #3554)