Support for Go and Custom builds

[aubelsb2]

Description

This adds support for

• Go 1.14.6
• Custom builds (ie makefile support) - (Which you need to use with Go where it isn't just a binary due to a bad go implementation)

Please note; you can't simply install the Go module from apk because it's compiled with musl not libc, so you have to download it.

Adds Feature or Fixes: # (issue)

• [x] I have performed a self-review of my own code - it works in my env
• [x] I have made corresponding changes to the documentation
• [x] Any dependent changes have been merged and published in downstream modules
• [x] The test workflow is passing locally

Screenshots/GIFs

[twebber90]

@aubelsb2 thanks for the PR! Is there any usage documentation that should be added to get this working correctly with GO?

[aubelsb2]

All the documentation is specific to aws sam cli.. This should "just work" as much as aws sam cli usually does. (Ie nothing special should be needed.)

Same with the custom build.. Which is what I'm doing by a make file being present in the source directory:

.PHONY: build

build-<function name>:
    GOOS=linux GOARCH=amd64 go build -o handler .
    mv handler $(ARTIFACTS_DIR)
    cp -r templates $(ARTIFACTS_DIR)

But that's normal aws sam cli stuff. I don't think it fits in the documentation you have here.

But the only reason I'm using the custom build above is that i want to embed some other files (the template directory) in the zip file. (Otherwise the sam build seems to just build the executable without a zip!!)