fix(markdown): render table without extra newlines above

[TomJGooding]

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

Description

This PR looks to fix #3027 by adding new_line = False to the TableRowElement and TableDataElement.

Currently if a markdown table contains any empty cells, an extra new line is rendered above the table for every empty cell. See the screenshot in the linked issue for an example.

These extra newlines seem to be caused by this code in Markdown:

rich/rich/markdown.py

Lines 692 to 699 in 720800e

	should_render = (
	not context.stack
	or context.stack
	and context.stack.top.on_child_close(context, element)
	)
	if should_render:
	if new_line:
	yield _new_line_segment

I confess I'm not as familiar with the Rich codebase as I am with Textual, so please let me know if I'm on the wrong track here.

[TomJGooding]

Closed in favour of #3313.