Allow images with data scheme (#4305)

* Add UnitTest for images

allows image elements with https scheme

* Test images with data scheme

* Add allowedSchemesByTag

* Fix error  Strings must use doublequote  quotes

src/core/components/providers/markdown.jsx

@@ -46,6 +46,7 @@ const sanitizeOptions = {
         "td": [ "colspan" ],
         "*": [ "class" ]
     },
+    allowedSchemesByTag: { img: [ "http", "https", "data" ] },
     textFilter: function(text) {
         return text.replace(/"/g, "\"")
     }

test/components/markdown.js

@@ -24,6 +24,18 @@ describe("Markdown component", function() {
             const el = render(<Markdown source={str} />)
             expect(el.html()).toEqual(`<div class="markdown"><p><img src="http://image.source" title="Image title"></p>\n</div>`)
         })
+      
+        it("allows image elements with https scheme", function() {
+            const str = `![Image alt text](https://image.source "Image title")`
+            const el = render(<Markdown source={str} />)
+            expect(el.html()).toEqual(`<div class="markdown"><p><img src="https://image.source" title="Image title"></p>\n</div>`)
+        })
+
+        it("allows image elements with data scheme", function() {
+            const str = `<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==">`
+            const el = render(<Markdown source={str} />)
+            expect(el.html()).toEqual(`<div class="markdown"><p>` + str + `</p>\n</div>`)
+        })
 
         it("allows heading elements", function() {
             const str = `
@@ -51,6 +63,18 @@ describe("Markdown component", function() {
             expect(el.html()).toEqual(`<div class="renderedMarkdown"><div><p><img src="http://image.source" title="Image title"></p></div></div>`)
         })
 
+        it("allows image elements with https scheme", function() {
+            const str = `![Image alt text](https://image.source "Image title")`
+            const el = render(<OAS3Markdown source={str} />)
+            expect(el.html()).toEqual(`<div class="renderedMarkdown"><div><p><img src="https://image.source" title="Image title"></p></div></div>`)
+        })
+
+        it("allows image elements with data scheme", function() {
+            const str = `<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==">`
+            const el = render(<OAS3Markdown source={str} />)
+            expect(el.html()).toEqual(`<div class="renderedMarkdown"><div>` + str + `</div></div>`)
+        })
+
         it("allows heading elements", function() {
             const str = `
 # h1