Support output to stdout in `dy export` command

[StoneDot]

Current Behavior

The dy export command requires specifying an output file path with --output-file. When attempting to use /dev/stdout (or similar special files), the command fails because it tries to truncate the file.

Expected Behavior

Users should be able to output directly to stdout, allowing them to pipe the data to other commands without creating intermediate files.

Example use case:

dy export --table MyTable --output-file /dev/stdout | jq '.[] | select(.status == "active")'

Proposed Solution

Add special handling for stdout (e.g., detect /dev/stdout, -, or add a dedicated flag like --stdout) that skips the truncate operation and writes directly to stdout.

Benefits

• Enables seamless integration with other CLI tools via pipes
• Avoids creating temporary files for data processing pipelines
• Provides a more Unix-like experience for scripting and automation