Make the Marker Table copyable as text

[arai-a]

Related to #5730

When comparing two profiles, I often do the following:

• Filter the Marker Table for the events that I want to compare (e.g. "ScriptExecution")
• Copy the table to a text editor, like CSV/TSV style
• Fix the "Start" column relative to Navigation::Start
• Add some more important events (e.g. "FirstContentfulPaint")
• Tweak and annotate the table to make it easier to compare
• Compare the tables for two profiles

Here, the "copy the table" step is difficult.
My current option is to inspect the DOM node, and print innerText property, and fix the text ordering and the formatting,
but this is not simple task, as the text order doesn't match what's shown in the table.

It would be nice if the table provides a way to copy the content as text, e.g. CSV or markdown table,
for the entire table, or selected rows (so, make it possible to select multiple rows first)

┆Issue is synchronized with this Jira Task