[RUM-11388] Fix FileBasedConfiguration related issues

[sbarrio]

What does this PR do?

This PR aims to fix several issues with FileBasedConfiguration initialization of the SDK.

1.- Fixes a reported issue that makes it so directly passing a configuration json file enforces users to duplicate and nest another configuration property for it to work, ignoring the structure defined on datadog-configuration.schema.json. Doing so makes the schema validator label the json configuration as invalid. I fixed it so it properly accepts the schema we enforce with just one configuration entry.

This means that creating a new FileBasedConfiguration can be done like so:

// 1.- File based configuration from .json
const configuration = new FileBasedConfiguration(require("../datadog-configuration.json"));

// 2.- File based configuration from .json and custom mapper setup
const configuration = new FileBasedConfiguration( {
   configuration: require("../datadog-configuration.json").configuration, 
   errorEventMapper: (event) => event, 
   resourceEventMapper: (event) => event, 
   actionEventMapper: (event) => event}
);

2.- Removes the automatic loading of a datadog-configuration.json file by not passing a config file to FileBasedConfiguration(). The way in which this was done was flimsy, as it relied on jumping out of node_modules up to the root app folder. This worked most of the time but it caused an issue generating a require cycle that made 2 of our internal enums to be undefined at runtime (TrackingConsent and SdkVerbosity).

3.- Updates the FileBasedConfiguration tests to be more thorough and cover edge cases properly.

4.- Expands the example app showcasing different ways to provide a configuration object to the DatadogProvider, including FileBasedConfiguration schemes.

Motivation

FileBasedConfiguration should consistently work across the board.

Additional notes

This is a breaking change, as the option of automatically looking for a config.json file without having the user provide a specific path when creating a FileBasedConfiguration object will cease to work.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)
• If this PR is auto-generated, please make sure also to manually update the code related to the change

[buraizu]

Just flagging some typos and suggesting a few other updates for consistency

[sbarrio]

Just flagging some typos and suggesting a few other updates for consistency

@buraizu Hi, thanks for raising all those typos 🙇

If you don't mind, I'll open a separate PR with your changes, as this specific PR is aimed toward a feature branch, and I think it's better to apply these corrections directly on develop.

EDIT: I've opened a PR with these fixes here.

[cdn34dd]

So now we will no longer try to resolve the configuration file ourselves automatically ? We'll require it to be passed so we don't have to rely on that flaky path correct ?

[sbarrio]

Exactly, passing a specific path to the configuration file will be mandatory on v3 and we won't try to guess it on our own as it was prone to errors and ended up being flimsy.