Rich text editor & viewer | Support for absolute link

[vivinkrishna-ni]

Pull Request

🤨 Rationale

1. Add absolute links in the editor by either pasting or manually entering a URL (HTTP/HTTPS).
2. The input and output for absolute links in Markdown follow the AutoLink format in the CommonMark flavor i.e. <URL>.
3. Links in the viewer will render as nimble-anchor. Part of Create a new anchor pattern to share styles across nimble components #1372
4. Links in the editor will render as <a> as we have few constraints in rendering nimble-anchor in the editor. Render "nimble-anchor" in rich text editor #1516

👩‍💻 Implementation

Rich text editor:

1. Installed @tiptap/extension-link to enable link in editor.
2. Configuring the following settings for the link in the editor:
   • Preventing users from opening a link in the editor by disabling the openOnClick
   • Disallowing users from pasting a link to an already selected word by disabling linkOnPaste, especially since hyperlinks are not supported for the initial pass.
   • Add Regex to validate that the entered/parsed URL conforms to the HTTPS/HTTP protocol. URLs not using HTTPS/HTTP will be displayed as plain text.
3. Adding custom link serializer for autolink in markdown-serializer.ts.
4. Preventing the application of additional formatting, such as bold or italics, to a link by using excludes: '_'. This is because CommonMark's autolink does not support the simultaneous application of another formatting within the link, making it impossible to render a specific part of the link in autolink markdowns, like <https://**nimble**.ni.dev>.

Rich text viewer (or markdown-parser):

1. Rendering links as nimble-anchor by updating the schema in markdown-parser.ts.
2. Validate if the links in the input markdown string are HTTPS/HTTP.
3. Normalize the link text to render the link as is, instead of updating the link text if it contains any encoded or non-ASCII characters.

🧪 Testing

1. rich-text-editor.spec.ts:
   1. "Absolute link interactions in the editor" - These tests cover user interactions with the editor like typing or copying and pasting the links. This includes testing the validate in index.ts (only HTTP/HTTPS), assessing links within various nodes, and restricting the application of other marks (bold/italics) to the links within the editor.
   2. "Absolute link markdown tests" - These tests ensure the parsed links are rendered as <a> tags and not as nimble-anchor within the editor. This distinction arises because we have adjusted the schema of the link in the markdown-parser.ts to parse it as a nimble-anchor. It also covers getMarkdown is the same as setMarkdown for links similar to the tests pattern we followed for other marks and nodes.
2. markdown-parser.spec.ts:
   1. "Absolute link" - These tests cover more in-depth of link formats that could possibly converted into links when parsed from a markdown string. It verifies autolink, validateLink, and normalizeLinkText in tokenizer rules and configurations set in the markdown-parser.ts.
3. markdown-serializer.spec.ts:
   1. These tests ensure only the text content(not href) in the <a> tag is serialized to autolink markdown string.
   2. It also covers how other marks (bold/italics) are ignored when the link is wrapped within it.

✅ Checklist

• I have updated the project documentation to reflect my changes or determined no changes are needed.