Add support for running DynamoDB within docker

[henhal]

This adds support for running DynamoDB using docker.
It relies on 99x/dynamodb-localhost#64, which is still open, so this PR is for now for initial discussion on the interface change. And in fact, since options are passed through to dynamodb-localhost, I don't anticipate any changes to be needed except for in the CLI argument parsing and the README. I wanted to get some feedback on if this setup with two additional options is good. :)

Fixes issue #277

Changes: Document docker options and pass to dynamodb-localhost

Demo Link: N/A

Screenshots for the change:

[ixartz]

Thank you for merging the other PR!

@AshanFernando, could also review this and merge if it looks good!

[henhal]

@ixartz I should add that I should probably test this a bit more, and of course also step the dependency to dynamodb-localhost in package.json, and take any feedback on the options structure etc.

[ixartz]

@henhal, Actually I'm good with everything. I have checked your suggested change it looks good to me.
I'm good to quickly have a working version and then, we can improve afterwards.

[henhal]

@ixartz @AshanFernando or whom it may concern: I've verified that this works with no further changes, by setting up a project with docker: true in my serverless.yml. So this PR basically just needs to bump the version of dynamodb-localhost as per 99x/dynamodb-localhost#64, once available.

[AshanFernando]

@henhal I've merged the PR. Thanks for verifying it.

[sarthakg-newzera]

Can this also be done for dynamodbStream?

[peebles]

Am I going crazy? I npm-install this on my x86 Mac (using node14.x and 16.x), and the package.json says 0.2.40, but the README.md makes NO mention of docker:true and setting docker:true in serverless.yml seems to have no effect ... it tries to run java and bombs.

But the README.md here in github does mention docker:true, and the version in package.json is 0.2.40.

After npm-install:

$ grep version node_modules/serverless-dynamodb-local/package.json 
  "version": "0.2.40"
$ grep -i docker node_modules/serverless-dynamodb-local/README.md 
$

In README.md:

...
## Features
* Install DynamoDB Local
* Start DynamoDB Local with all the parameters supported (e.g port, inMemory, sharedDb)
* Table Creation for DynamoDB Local

## Install Plugin
...

[henhal]

@peebles You're not crazy. This change requires 99x/dynamodb-localhost#64 - which is merged - but no new release has been made. My PR with the readme changes made it into the master branch, but what's missing is for a maintainer of dynamodb-localhost to make a new release and then for the maintainer of this package to reference that new release in package.json Unfortunately none of those things have been done for many months now.

As a workaround consider #277 (comment)

[peebles]

The worst part of the issue is the README.md not matching reality. The doc here at serverless.com is taken from the README.md too: https://www.serverless.com/plugins/serverless-dynamodb-local. Spent a long time trying to get it to work before I finally started looking at the source under my node_modules. Perhaps the README should be backed out, until everything gets merged properly.