[c2pa-dash-0003] (C2PA/Streaming) Better handling of mime type in c2pa validation

[spetrangeli]

dash.js/samples/c2pa/plugin-dash/c2pa-dash-plugin.js

Line 28 in e70ea93

initFragment[tag] = new Blob([chunk.bytes], {type: 'video/mp4'});

and

dash.js/src/streaming/C2pa.js

Line 54 in e70ea93

initFragment[tag] = new Blob([e.response], {type: 'video/mp4'});