[aspnetcore] Include appsettings.Development.json

[DanielHabenicht]

Previously the file was not used and not part of the output although it already exists as template

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[DanielHabenicht]

@mandrean (2017/08) @frankyjuang (2019/09) @shibayan (2020/02) @Blackclaws (2021/03) @lucamazzanti (2021/05) ready for review from my side

[wing328]

@DanielHabenicht thanks for the PR, which looks good to me.