collect-wsl-logs.ps1 should warn users when a required tool is not installed

[andremueiot]

Is your feature request related to a problem? Please describe.
WSL developers need complete logs in order to investigate issues. Certain logs can only be collected when proper tools are installed on Linux.
It's common for people to miss these details when reading the documentation. Others don't read docs at all. This can result in incomplete logs and prevent issues from being root caused.

Describe the solution you'd like
It would be very useful for the script that collects the logs to check if the required tools are installed and write a clear warning in case some are missing, making it clear to the user that they should seriously consider installing the tool.

Describe alternatives you've considered
An alternative considered would be failing the script's execution when a tool is missing, but that is probably too drastic.
There might be a legitimate reason for the tool to not be installed, and blocking the collection of the other logs would arguably be worse.

Additional context
Suggested warnings:
WARNING: tcpdump not found on WSL. For a more complete log collection install tcpdump.
WARNING: iptables not found on WSL. For a more complete log collection install iptables.

[github-actions]

Logs are required for review from WSL team

If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'.
Otherwise, please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs

Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The script will output the path of the log file once done.

If this is a networking issue, please use .\collect-wsl-logs.ps1 -LogProfile networking instead, following the instructions in Collect WSL logs for networking issues

Once completed please upload the output files to this GitHub issue.

See Collect WSL logs (recommended method).

If you choose to email these logs instead of attaching them to the bug, please send them to wsl-gh-logs@microsoft.com with the GitHub issue number in the subject, and include a link to your GitHub issue comment in the message body, and reply with '/emailed-logs'.

[andremueiot]

Working on a fix.