Add Select (dropdown) column type to tables

[jreyesr]

Hello! I've been playing around with Lowcoder, and I wanted to have dropdowns in editable table columns, as requested in #412. I couldn't find it, so I quickly threw this together.

Let me know if any more changes are needed! I tried to touch similar files to those touched by d92f917, which added the Number column type, so hopefully not too many things have been forgotten.

Proposed changes

This PR adds a new Select column type to tables. It's specifically intended to allow inline edits to present a dropdown so users get some guidance on the allowed values, instead of a simple text field.

Example: the following screenshots show a Table component with its standard data (10 users with an ID, name, date and department). However, the Department column (which is usually a Text column) has been changed to a Select column and marked as Editable:

When editing a user's Department (by double-clicking that cell), it transforms into a dropdown:

Of course, clicking on the dropdown displays the available choices:

Once a different choice has been selected (and the cell unfocused), the cell is marked as having pending changes:

Saving the table emits an event which has the changed cell as part of the table's changeSet, where it would be handled as any other change. This notification is triggered on the Save Changes event of the table, and it prints {{table.changeSet}}:

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

[netlify]

‼️ Deploy request for lowcoder-cloud rejected.

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[FalkWolsky]

Thank you million times! What a valuable contribution!

The base branch was changed.

[netlify]

👷 Deploy request for lowcoder-test pending review.

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🔨 Latest commit	8f6ea6f

[FalkWolsky]

Thank you very much for this valuable contribution!!