[c++ pistache server] Support basic query handling

[etherealjoy]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
• Filed the PR against the correct branch: master, 3.3.x, 4.0.x. Default: master.
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Description of the PR

• Add helpers for primitive de-serialization
• Remove warnings due to unneeded commas
• Deserialize basic types in queries
• Add dependencies chain for external libraries
• Fixes wrong parameter passed to API Handler
• Splitted the serialization of primitive types which are not handled by the json library

Fixes #257
Fixes #768
Fixes #638
@stkrwork @MartinDelille @wing328 @fvarose @ravinikam

[etherealjoy]

Missing support for ByteArray, Date and DateTime

[etherealjoy]

@CyrilleBenard
Could you please check if the above items are solved?

[CyrilleBenard]

Confirmed, #257 #638 and #768 are fixed with this PR 👍

[CyrilleBenard]

I wonder why you use the Pistache::Some method, could you explain in few words ? (just to improve my knowledge)

[etherealjoy]

Pistache::Some returns an Pistache::Optional so that you can check whether it is set or not set.

[wing328]

@etherealjoy thanks again for the PR, which is included in the v3.3.0 minor release: https://twitter.com/oas_generator/status/1046941449609068544