Expose RetryClient in NetworkTileProvider initialisation

[MichalTorma]

This pull request adds optional parameter RetryClient for NetworkTileProvider. I made this fork to scratch my own itch with some stubborn tile servers that are either too slow or don't follow the standard conventions. Some servers require longer cooldown between the requests therefore more than 3 retries are needed (as was the default in NetworkImageWithRetry).

[ibrierley]

So, out of interest, what would be a good example code that someone would use as the optional RetryClient ?

[MichalTorma]

So, out of interest, what would be a good example code that someone would use as the optional RetryClient ?

Hi there,
Here is an example of layer definition that I needed for one open server that replies 200 every-time you ask for something, but response either contains png as one would expect, or content-type is different and error message (too many requests) is inside the response body. (don't as me why :D - It's Norwegian national cartography server...). I also needed to increase the number of retries because it is a bit sluggish...

        TileLayerOptions(
            tileProvider: NetworkTileProvider(
                retryClient: RetryClient(
              Client(),
              retries: 10,
              when: (p0) => p0.headers['content-type'] != 'image/png',
            )),
            wmsOptions: WMSTileLayerOptions(
                baseUrl: 'https://openwms.statkart.no/skwms1/wms.topo4?',
                layers: ['topo4_WMS'],
                version: '1.3.0',
                format: 'image/png',
                crs: const Epsg3857(),
                transparent: false)),

[JaffaKetchup]

This will conflict with #1294, but it's not too much of an issue, so I'm happy for it to be merged ahead.

[JaffaKetchup]

@MichalTorma Hi there,

I've had to make some unexpected changes to #1294, which includes the changes that PR made. You can see the commit which did this: ad2adb6.

As a result, I'm going to close this PR. Many thanks for your contribution, it's greatly appreciated!