[Feature] Add tzdata into docker image to support customize timezone through environment variables "TZ"

[bobwng]

Is your feature request related to a problem? Please describe.
We have no way to setup correct timezone base on current docker image without any modification.

Describe the solution you'd like
Add below line into Dockerfile:

RUN apk add tzdata

Or modiby below line

RUN chmod -x /wait-for.sh && chmod -x /docker-entrypoint.sh && apk add --update --no-cache git nginx s6 curl sudo \

to:

RUN chmod -x /wait-for.sh && chmod -x /docker-entrypoint.sh && apk add --update --no-cache git nginx s6 curl sudo tzdata \

And then we can use environment variables TZ to customize the timezone.

Additional context