fix(http_requests): allow blob: to prepend URL string

[xgui3783]

This is my first PR in this repo. Apologies if I have made any mistakes.

Currently, if the data source originates from the web (thus have the URL of https?://), the parseUrl function correctly parses the protcol, host and path.

In our usecase, we often need to download the entire (nifti) image, preprocess them, and generate a blob URL. According to mdn doc on URL.createObjectURL , it creates a URL with blob: prepended. This fails the check as it is implemented currently.

This PR addresses this issue.

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[xgui3783]

I signed it.

(Looks like I have initiated the CLA, but not signed it until a few seconds ago)

[jbms]

Does this actually work, though? It looks like it just discards the "blob:" prefix when parsing.