feat: add key action to table in markdown

[seonim-ryu]

Please check if the PR fulfills these requirements

• It's the right issue type on the title
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes/features)
• Docs have been added/updated (for bug fixes/features)
• It does not introduce a breaking change or has a description of the breaking change

Description

Use case 1: tab key

Pressing the tab key in the markdown table moves the cursor cell by cell.

Before

• tab : The text is indented in the cell.
• shift + tab : The text is outdented in the cell.

After

• tab :
  • If it is not the last cell in a row, pressing tab moves to the next cell.
  • For the last cell in a row, pressing tab moves to the first cell in the next row.
  • If you press tab in the last cell of the table, he cursor is positioned outside the table (ending point).
• shift + tab :
  • If it is not the first cell in a row, pressing shift + tab moves to the previous cell.
  • For the first cell in a row, pressing shift + tab moves to the last cell in the previous row.
  • If you press shift + tab in the first cell of the table, the cursor is positioned outside the table (starting point).

Use case 2 : enter key

Pressing the enter key in the markdown table adds the syntax for the new row.

Before

• Cell of table head : Table syntax is broken.
• Cells in delimiter row : Table syntax is broken.
• Cell of table body : A newline is added to the text in the cell and rendered with the remaining columns filled.

After

• Cell of table head : Table syntax is broken.
• Cells in delimiter row : A new row with as many columns as the current number of columns is added.
• Cell of table body :
  • A new row with as many columns as the current number of columns is added.
  • When adding a new row in the last row, if the current row is empty, remove the current row.

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Thank you for your contribution to TOAST UI product. 🎉 😘 ✨

[lja1018]

[07/28] 리뷰완료.
고생하셨습니다!

[js87zz]

키맵핑 부분은 command로 별도 분리하는게 더 깔끔하지 않을까요?

[seonim-ryu]

커맨드로 분리해서 적용한 커밋입니다ㅎㅎ

c15692c