indi-gphoto support saving SDCardImage for Fuji DSLRs

[LuckyEddie47]

At least some Fuji DSLRs, for example the X-T2, have a quirk in their gphoto memory usage. Although the gphoto driver uses the camera's internal RAM for the image destination these cameras require an explicit erase of the image in RAM after download rather than allowing implicit overwriting.

This is handled by the SDCardImage option on the Image Settings tab being set to 'Delete'. Failure to set this will result in images being captured only until the camera's internal RAM buffer is full after which the camera is locked up until power cycled. This option works well but is current only saved in the configuration files for cameras that target their SD Card instead of their internal RAM.

A modification is required to the configuration save function to allow saving of this setting for Fuji DSLRs.

To Reproduce

1. Open Fuji DSLR driver.
2. Switch to Image Settings tab and set SD Card Image to Delete.
3. Switch to Options tab and Save configuration.
4. Close Fuji driver.
5. Re-open Fuji driver, switch to Image Setting tab and observe that the SD Card Image setting is not restored.
6. The missing setting is also observed to be absent in the saved Fuji *********.xml configuration file.

Expected behavior

1. Open Fuji DSLR driver.
2. Switch to Image Settings tab and set SD Card Image to Delete.
3. Switch to Options tab and Save configuration.
4. Close Fuji driver.
5. Re-open Fuji driver, switch to Image Setting tab and observe that the SD Card Image setting is restored as saved.

[LuckyEddie47]

Fixed in commit 249935d