Draft: Reorg GraphQL quote topic

[keharper]

Purpose of this pull request

This pull request (PR) updates the GraphQL quote endpoint to include all the 2.3.2 community contributions

Related issue

Affected DevDocs pages

• https://devdocs.magento.com/guides/v2.3/graphql/reference/quote.html

This PR also adds 8 new topics and several include files.

Links to Magento source code

whatsnew
The GraphQL quote endpoint adds numerous mutations for 2.3.2. Each mutation is documented separately. The GraphQL release notes lists these new mutations.

[keharper]

Externally-viewable draft. The quote documentation begins here.

https://devdocs.magedevteam.com/424/guides/v2.3/graphql/reference/quote.html

Adding @rogyar as a reviewer as mentioned in #4316 His updated example is here: https://devdocs.magedevteam.com/424/guides/v2.3/graphql/reference/quote-add-simple-products.html

I would appreciate it if @atwixfirster or someone with a good working knowledge of the Quote endpoint reviewed the all the new topics.

[erikmarr]

Looks great! Just some minor editorial feedback.

[ghost]

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[TomashKhamlai]

, can be omitted in the request body according to Graphql Docs. It can improve the clearness of the examples.