Multidate WCS requests are broken for both WCS1 and WCS2

[SpacemanPaul]

Reported by jonathan:

multi-date for 1.0.0

Unexpected server error: 'WCSFormat' object is not subscriptable

https://ows.dea.ga.gov.au/wcs?request=GetCoverage&service=WCS&version=1.0.0&coverage=fcp_seasonal_green_veg&crs=EPSG%3A4326&format=netCDF&bbox=149.05%2C-35.32%2C149.17%2C-35.25&time=2018-09-01%2C2018-12-01&resx=0.01&resy=0.01

for version 2.1.0
so a single time works:
https://ows.dea.ga.gov.au/wcs?service=WCS&request=GetCoverage&version=2.1.0&format=application/x-netcdf&subsettingcrs=EPSG%3A3577&coverageid=fcp_seasonal_green_veg&rangesubset=PV_PC_10,PV_PC_50,PV_PC_90&scalesize=x(1024),y(307)&subset=y(-2811606.37,-2801958.92)&subset=x(-585380.79,-560682.416)&subset=time(%222018-12-01%22)

but adding an extra time breaks it
https://ows.dea.ga.gov.au/wcs?service=WCS&request=GetCoverage&version=2.1.0&format=application/x-netcdf&subsettingcrs=EPSG%3A3577&coverageid=fcp_seasonal_green_veg&rangesubset=PV_PC_10,PV_PC_50,PV_PC_90&scalesize=x(1024),y(307)&subset=y(-2811606.37,-2801958.92)&subset=x(-585380.79,-560682.416)&subset=time(%222018-09-01%22,%222018-12-01%22)

Unexpected server error: 'ProductBandQuery' object has no attribute 'center_time'

adding a third time
https://ows.dea.ga.gov.au/wcs?service=WCS&request=GetCoverage&version=2.1.0&format=application/x-netcdf&subsettingcrs=EPSG%3A3577&coverageid=fcp_seasonal_green_veg&rangesubset=PV_PC_10,PV_PC_50,PV_PC_90&scalesize=x(1024),y(307)&subset=y(-2811606.37,-2801958.92)&subset=x(-585380.79,-560682.416)&subset=time(%222018-06-01%22,%222018-09-01%22,%222018-12-01%22)

Unexpected server error: Unknown string format: 2018-09-01","2018-12-01

[SpacemanPaul]

For the "3 times" case, this is a limitation/misunderstanding of WCS2 subsets. You cannot set an arbitrary list of dates in WCS 2 (as you can in WCS 1) - you can set a single date, or two dates, which signify the lower and upper bounds of the range of available dates that you interested in. 3 dates is an invalid request - although the detection and error message could be cleaner.

[SpacemanPaul]

Fixed in #799