Improve the usability of GenericContainer

[bsideup]

What was changed:

• store envs as Map, not List, so that one can get all envs as a map:

container.getEnvMap()

• add withEnv with mapper:

.withEnv("JAVA_OPTS", it -> it.orElse("") + " -javaagent:/foo.jar")

• use READ_WRITE bind mode if none was provided:

.withFileSystemBind("/foo", "/bar")

Also deprecated some methods from Container interface like fetchDockerDaemonInfo because we don't want to have them in our public API

[rnorth]

@bsideup CircleCI failure? https://circleci.com/gh/testcontainers/testcontainers-java/829
🤔

[rnorth]

Is this related to the change? Same question for deprecation getContainerInfo().

I don't mind deprecating these, as it makes things cleaner, but would it be possible to have a comment indicating a recommended alternative approach?

[rnorth]

Only the strange CircleCI failures and one minor comment re deprecated methods, otherwise LGTM!

Oops - also, please could you add an entry to the changelog?

[bsideup]

@rnorth CircleCI failed because it was using the old configuration:
https://circleci.com/gh/testcontainers/testcontainers-java/829#config/containers/0

I've added deprecation notes and entries to CHANGELOG.md :)