Update Dockerfile to include timezone and culture information

[ivarne]

"PdfGeneratorSettings": {
   "DisplayFooter": true
}

requires globalisation and timezone info in docker images.

This will ensure that new apps gets this setting by default.

# Add globalization timezone support
RUN apk add --no-cache icu-libs tzdata
ENV DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=false

Related Issue(s)

• Add an optional footer for the generated PDF app-lib-dotnet#792

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)
• All tests run green

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[martinothamar]

LGTM, the docs will just have to say something like "if your app was created before xxx, you will have to add these two lines to your Dockerfile..."