Handle content type after an import with gatsby-source-contentful

[kevee]

Gatsby source contentful imports Rich Text then resolves all the child nodes, which means embedded entries look like the following node. This PR just checks that the content type of a target embedded entry isn't also located in target.sys.contentType.sys.id.

{
      "data": {
        "target": {
          "sys": {
            ...
            "contentType": {
              "sys": {
                "type": "Link",
                "linkType": "ContentType",
                "id": "contentInlineImage"
              }
            }
          },
          "fields": {
            ...
          }
        }
      },
      "content": [],
      "nodeType": "embedded-entry-block"
    },

[codecov]

Codecov Report

Merging #4 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
+ Coverage   98.85%   98.86%   +0.01%     
==========================================
  Files          13       13              
  Lines         174      176       +2     
  Branches       48       49       +1     
==========================================
+ Hits          172      174       +2     
  Misses          2        2

Impacted Files	Coverage Δ
src/rich-text-to-jsx.js	98.79% <100%> (+0.02%)	⬆️

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[connor-baer]

Great improvement, thanks for the contribution! 👏

[connor-baer]

This change is included in v2.1.1.