Throw InvalidRequest exception on invalid CURL request

[alextech]

Fixes

#90

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation about the functionality in the appropriate .md file
• I have added in line documentation to the code I modified

Short description of what this PR does:

• Currently, if there are any issues with requests, the library exists silently with response code 0. This creates confusion about whether the problem was detected at SendGrid server or locally, what should be done next. This PR introduces an exception thrown with message from CURL about why actually request fails.
• Not doing a specific exception as outlined in Document and throw an error to help people with CURLOPT_SSL_VERIFYPEER issues #90 because
  1. there are many reasons why request (SSL or not) could fail, and that was just a single example. No point replicating every possible CURL error into an exception.
  2. Difficult to unit test full working connection to replicate network conditions.

[SendGridDX]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #99 into master will increase coverage by 3.29%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #99      +/-   ##
=======================================
+ Coverage    84.7%   88%   +3.29%     
=======================================
  Files           3     4       +1     
  Lines         170   175       +5     
=======================================
+ Hits          144   154      +10     
+ Misses         26    21       -5

Impacted Files	Coverage Δ
lib/Exception/InvalidRequest.php	100% <100%> (ø)
lib/Client.php	85.31% <100%> (+3.75%)	⬆️

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[Rezouce]

Hey,
Do we have any idea on when this PR will be merged?

[thinkingserious]

Hello @Rezouce,

I do not, but for this issue to gain priority in our backlog, we need additional +1's or comments.

My apologies for the delay and thanks for your patience.

With Best Regards,

Elmer

[DvdGiessen]

Just reviewed these changes and they're basically what I envisioned when I wrote sendgrid/sendgrid-php#328 (comment). Looks good to me, lets get this moving!

[reFX-Mike]

Why is this not merged already? Can someone for Sendgrid please explain what the holdup is? This is an important issue that needs to be fixed.

[thinkingserious]

Hello @alextech,

Thanks again for the PR!

We want to show our appreciation by sending you some swag. Could you please fill out this form so we can send it to you? Thanks!

Team SendGrid DX

[reFX-Mike]

Now somebody just needs to push this to packagist, so we can actually benefit from this fix.