Use Bash for linux platforms

[gmaiorov]

Summary

Use Bash on linux-based OS to fix Bash-specific commands in BashTool.kt to resolve #1188.

Changes

Reworked buildShellCommand() function:

• it uses when statement now to add some platform-related flexibility;
• it uses bash on linux platforms;
• it still uses sh on other non-windows platforms where bash may be missing by default.

[vercel]

@gmaiorov is attempting to deploy a commit to the carlrobertohgmailcom's projects Team on Vercel.

A member of the Team first needs to authorize it.

[carlrobertoh]

Many thanks for your contribution!

Looks good, but I wonder if it's possible to use the Koog's in-built JvmShellCommandExecutor instead of relying on our own custom ProcessBuilder. They're practically doing the same thing.

[gmaiorov]

Thanks for fast feedback!

While it seems that JvmShellCommandExecutor would address my usecase, I personally don't like hardcoding Bash for all platforms, and that would require some refactoring just for a sake of it.
And you're handling IO basically same, so I see no profit in that change.