Fix FileTileProvider to work on the web

[mu-dawood]

This pr create two files file_tile_provider_io.dart and file_tile_provider_web.dart
and export the right one

[JaffaKetchup]

Thanks for this - I saw your note on the other PR. Just running checks now, should be able to review tomorrow or soon.

[JaffaKetchup]

LGTM. Haven't fully tested, but it doesn't look like it should cause any problems. If it's not too much of a hassle, can you remove the 'Podfile', as it's unrelated to this commit (I think)? Otherwise I'm happy to merge.

[ibrierley]

I'm a bit undecided on this one, as not enough experience on the flutter web side to know what's best. It doesn't feel like the Podfile is needed as previously mentioned, so I think that could go.

Regarding the other bits, something "feels" odd about having a FileTileProvider that uses a NetworkImage...but I can understand why the web makes this a bit messy. Wouldn't one simply not use it, or does it create an error when building for the web (again, I'm not so familiar with that)?

[JaffaKetchup]

As @ibrierley also said, please remove the 'Podfile' as it is not directly related to this PR.
If you can also explain why NetworkImage is used, that would be good: I'm assuming that is just how the Flutter framework works, but I might be wrong.

[mu-dawood]

The browser can not access file system directly it can accept blobs

so in flutter web you have to load the image using NetworkImage instead of FileImage

[JaffaKetchup]

LGTM, and that explanation makes sense. @ibrierley?

[ibrierley]

Yeah, I think I'm happy with that, and I think it's all straightforward enough to amend should a better strategy evolve with the web stuff. Will give a retest and merge if all still looks ok.

[ibrierley]

All good on Android and Web for me.