gh-94525: Double left click to smart select meaningful selection

[znsoooo]

Features:

• Highlight the selected word.
• Click the boundaries of string to select the whole string. (by using pre-tagged TAG in tk.Text)
• Quick select the whole comments by click the comment mark (# sign).
• Quick select the matched parentheses, including in comments.
• Select a row by double-click the end of line.
• Multi-line select by click the colon mark or click the space in indent.
• Select escape character (\n, \xhh, \uxxxx, …).
• …

Screen record:

• Issue: IDLE: Double click text in editor to select more meaningful area #94525

[github-actions]

This PR is stale because it has been open for 30 days with no activity.