Replace use of camera manufacturer with maker

[Phemisters]

Related darktabke issue: darktable-org/darktable#18897

Replace uses of camera manufacturer with camera maker. I'm not sure if the sentences now sometimes read a little oddly, but this makes it more consistent with darktable itself.

I have not changed other uses of manufacturer (e.g. printer or GPU manufacturer).

[elstoc]

On reflection, while I'm ok with using the term "maker" in darktable itself (since the exif field is maker), reading the proposed changes, I think the term "manufacturer" is better in all these contexts in the documentation.

Perhaps the only exception might be the reference to the "maker ID" in which case I would surround it in quotes to make it clear we're quoting the exif field name.

The PR is much appreciated to allow me to see all the uses in context in one place.

[Phemisters]

Perhaps the only exception might be the reference to the "maker ID" in which case I would surround it in quotes to make it clear we're quoting the exif field name.

Updated as suggested.

[elstoc]

LGTM, thanks!