Ok i managed to make it worked. So my solution for the moment is based on this docker image https://hub.docker.com/r/senscode/sqlanywhere12

Here is the exact solution :

1) pull the sqlanywhere12 image :

(in powershell)
docker pull senscode/sqlanywhere12:latest

2) extract the sqlanywhere12 files from it to your computer (ex : in new folder "unix" on your desktop)

docker cp sqlanywhere12:opt/. "C:\Users\"youraccount"\Desktop\unix\."

3) create a new Dockerfile somewhere (ex : C:\Users\"youraccount"\Desktop\) with this code inside :

FROM microsoft/dotnet:2.1-aspnetcore-runtime
EXPOSE 80
EXPOSE 443

RUN apt-get update
RUN apt-get install unixodbc-dev unixodbc-bin unixodbc -y

ENV LD_LIBRARY_PATH /opt/sqlanywhere12/lib64

4) Build it with docker :

docker build -t base-sqlanywhere12-dotnet:2.1-aspnetcore-runtime -f "C:\Users\"youraccount"\Desktop\Dockerfile" "C:\Users\"youraccount"\Desktop"

5) Copy the sqlanywhere12 files from your machine to this container :

docker cp "C:\Users\"youraccount"\Desktop\unix\." basenet:/opt/

6) Commit this as new image (you need to be logged-in to yourdockerhubaccount)

docker login --username=yourdockerhubaccount
docker commit basenet yourdockerhubaccount/base-sqlanywhere12-dotnet:latest

7) Push to yourdockerhubaccount

docker push yourdockerhubaccount/base-sqlanywhere12-dotnet

8) In your SnapDevelop project replace the first line of your Dockerfile :

FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base

by :

FROM yourdockerhubaccount/base-sqlanywhere12-dotnet:latest AS base

9) You can publish your API and access SQL Anywhere database from docker.