Reorganize examples into categorized folders

[matthewkeil]

Reorganized the examples into categorized folders and updated the test_all script for the new directory format.

Here is the layout that was used. Each "category" has several examples and each example can have multiple versions of native integration (nan, node-addon-api, napi):

REPO_ROOT
├── test_all.js
├── package.json
├── README.md
└── src
    ├── 1-getting-started
    │   ├── example1
    │   │   ├── nan
    │   │   ├── node-addon-api
    │   │   └── napi
    │   ├── example2
    │   └── example3
    ├── 2-js-to-native-conversion
    ├── 3-context-awareness
    ├── 4-references-and-handle-scope
    ├── 5-async-work
    ├── 6-threadsafe-function
    ├── 7-events
    └── 8-tooling

The test_all.js file was updated to reflect the new structure and I also massaged the output a bit at the end for a bit more feedback. The file was not originally running the test script in each package, it was just running install. I added a bit of logic to run the test script found in the package.json and then output whether the install works/doesnt, if a test was found/wasnt and if the test ran successfully. I found one that did not run successfully because the script was not setup in the package.json. There is a file in there that looks like a "test" case but its an infinite loop. Will fix that in a subsequent PR.

Updated test_all.js output (after the output that was shown before):

passed: /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/thread_safe_function_round_trip/napi
passed: /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/threadsafe-async-iterator/node-addon-api
passed: /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/typed_threadsafe_function/node-addon-api
no test found:
    /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/promise-callback-demo/node-addon-api
    /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/thread_safe_function_counting/node-addon-api
failed install:
    /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/general/6_object_wrap/napi
failed tests:
    /Users/matthewkeil/Documents/dev/chainsafe/node-addon-examples/threadsafe-function/thread_safe_function_with_object_wrap/node-addon-api

Questions for how to make this better:

1. Should the categories and examples be numbered so they show up in a pre-determined order?
2. Should the categories be placed in a src folder?

[matthewkeil]

@mhdawson @legendecas @gabrielschulhof @vmoroz got this updated per the discussion on the meeting last week.

Here is the example of what landing on the repo will look like after this merges:
https://github.com/matthewkeil/node-addon-examples/tree/mkeil/reorganize

[mhdawson]

@matthewkeil I think its starting to look good, but I think build_with_cmake which is still at the top level should likely be under the src/8-tooling directory?

[mhdawson]

LGTM with one suggestion/comment

[matthewkeil]

Just getting back from vacation. Thanks for pushing that commit @legendecas . If that was the only thing left feel free to merge when you guys are ready @mhdawson