[Feature] Add a Sentry configuration helper

[titouanmathis]

This PR adds a Sentry class to easily configure back-end and front-end integration of Sentry for WordPress.

It can be used as follows in your configuration file (wp-config.php or another):

use Studiometa\WPToolkit\Sentry\Sentry;

Sentry::configureWithDefaults( $root_dir );

The $root_dir variable is used to read the version of your project from a package.json file at the root of your project. The version is made of the package name and version properties.

The following environment variables can be used to configure Sentry:

SENTRY_DSN=""
SENTRY_JS_LOADER_SCRIPT=""
SENTRY_ENV=""
SENTRY_SAMPLE_RATE=0.0
SENTRY_TRACES_SAMPLE_RATE=0.0
SENTRY_PROFILES_SAMPLE_RATE=0.0

[codecov]

Codecov Report

Attention: Patch coverage is 22.80702% with 44 lines in your changes are missing coverage. Please review.

Project coverage is 62.81%. Comparing base (2ebb179) to head (2fba3f6).

❗ Current head 2fba3f6 differs from pull request most recent head 69b9175. Consider uploading reports for the commit 69b9175 to get more accurate results

Files	Patch %	Lines
src/Sentry/Sentry.php	0.00%	44 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #29      +/-   ##
=============================================
- Coverage      67.40%   62.81%   -4.59%     
- Complexity       182      194      +12     
=============================================
  Files             12       14       +2     
  Lines            497      554      +57     
=============================================
+ Hits             335      348      +13     
- Misses           162      206      +44     

Flag	Coverage Δ
unittests	62.81% <22.80%> (-4.59%)	⬇️

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