Rewrite using TypeScript

[GeorgySk]

• Fix styles that don't get passed from the "New" button.
• Fix missing button in full-page tables.
• Add a note in README about building the extension.
• Fix a default cursor changing to a text cursor after clicking a button.

[GeorgySk]

Clicking button suddenly broke. Currently, it throws this error:

content.js:125 Uncaught TypeError: Cannot read properties of undefined (reading 'querySelectorAll')
    at getRows (content.js:125:24)
    at buttonClickHandler (content.js:112:18)
    at HTMLButtonElement.<anonymous> (content.js:89:9)

[GeorgySk]

Clicking button suddenly broke. Currently, it throws this error:

content.js:125 Uncaught TypeError: Cannot read properties of undefined (reading 'querySelectorAll')
    at getRows (content.js:125:24)
    at buttonClickHandler (content.js:112:18)
    at HTMLButtonElement.<anonymous> (content.js:89:9)

The problem was due to a new element that was added before the table in one of the recent updates. The current way of searching for the table rows should be more robust.