Implement image building in the kyma alpha app push command

[Cortey]

Description
As in title

Changes proposed in this pull request:

• Build image from dockerfile
• Support cross-platform build to run containers on Linux/amd64 architecture
• Use the built image in created deployment

Related issue(s)
#2241

[pPrecel]

we've tested functionality using this Dockerfile:

FROM alpine:latest

WORKDIR /workspace

RUN apk update
RUN apk add go

COPY . /workspace

CMD [ "go", "run", "main.go", "--help", "&&", "sleep", "infinity" ]

and by running command:

go run main.go alpha app push --name test --dockerfile Dockerfile