fix(storage): percent-encode object key in cdn purge urls

[fresh55]

closes #298

a ? or # in an object key was read as the start of a query string or fragment, so the purge hit the wrong path:

purgeCache("folder/a?b#c.png")

before  DELETE /cdn/bucket/folder/a?b
after   DELETE /cdn/bucket/folder/a%3Fb%23c.png

this percent-encodes each path segment, same as supabase/supabase-js#2545.

upstream only did this for the two purge urls, not for sign/render/object, so i kept it to the same two.

i didn't put the encoding in GetFinalPath because the upload methods return that value back to the caller as the key.

[Tr00d]

Well done, thanks @fresh55 for your contributions 👏