feat: new custompages upload command (#1265)

Author: emilyskuo

__tests__/__fixtures__/custompages/complex-frontmatter/basic.md

@@ -0,0 +1,5 @@
+---
+title: This is the document title
+content:
+  body: frontmatter body
+---

__tests__/__fixtures__/custompages/complex-frontmatter/complex.md

@@ -0,0 +1,13 @@
+---
+title: This is the document title
+appearance:
+  fullscreen: true
+metadata:
+  description: A description
+  keywords: something, another
+  title: document
+privacy:
+  view: public
+---
+
+Body

__tests__/__fixtures__/custompages/existing-docs/not-a-markdown-file

@@ -0,0 +1,5 @@
+---
+title: This is the document title
+---
+
+Body

__tests__/__fixtures__/custompages/existing-docs/simple-doc.md

@@ -0,0 +1,5 @@
+---
+title: This is another document title
+---
+
+Another body

__tests__/__fixtures__/custompages/existing-docs/subdir/another-doc.md

@@ -0,0 +1,8 @@
+---
+title: This is another document title
+content:
+  type: html
+---
+
+<h1>Here we have an HTML file</h1>
+<p>This is a paragraph in an HTML file.</p>

__tests__/__fixtures__/custompages/existing-docs/subdir/html-file.html

@@ -0,0 +1 @@
+Body

__tests__/__fixtures__/custompages/mixed-docs/doc-sans-attributes.md

@@ -0,0 +1,7 @@
+---
+title: This is the document title
+appearance:
+  is-this-a-valid-property: nope
+---
+
+Body

__tests__/__fixtures__/custompages/mixed-docs/invalid-attributes.md

@@ -0,0 +1,7 @@
+---
+title: This is the document title
+hidden: true
+fullscreen: true
+---
+
+Body

__tests__/__fixtures__/custompages/mixed-docs/legacy-page.md

@@ -0,0 +1,6 @@
+---
+title: This is the document title
+slug: some-slug
+---
+
+Body

__tests__/__fixtures__/custompages/mixed-docs/new-doc-slug.mdx

@@ -0,0 +1,5 @@
+---
+title: This is the document title
+---
+
+Body

__tests__/__fixtures__/custompages/mixed-docs/not-a-markdown-file

@@ -0,0 +1,5 @@
+---
+title: This is the document title
+---
+
+Body

__tests__/__fixtures__/custompages/mixed-docs/simple-doc.md

@@ -0,0 +1,6 @@
+---
+title: This is the document title
+slug: some-slug
+---
+
+Body