Naming convention: enum and enum-like member names

[eladb]

Currently, we use two conventions for enum member names:

1. Enum.PascalCase (like lambda.Runtime.NodeJs8)
2. Enum.CAPS_SNAKE_CASE (like codebuild.LinuxBuildImage.UBUNTU_14_04_ANDROID_JAVA8_26_1_1)

It would be intractable to use pascal case for the 2nd example (Ubuntu1404AndroidJava82611...), and we should also be cognizant that jsii languages need to be able to delimit words for case conversions (see #980).

I am proposing that we standardize (at the jsii level) that all enum member and static property names will always be snake upper case (e.g. like C constants).

Any objections?

[rix0rrr]

This is going to be ugly AF in many many places. But I don't have a better solution :(

[RomainMuller]

I'm in favor of TRUMP_CASE.

This isn't going to look "pretty" in JS/TS, but that's a sacrifice I'm willing to make.

The current problem outlined in #980 and several other issues (some in awslabs/jsii even) can't really be fixed in another way (that looks constant-y).

[eladb]

@skinny85 suggests Ubuntu_14_04_Android_Java8_26_1_1

[eladb]

TRUMP CASE IT IS