Add new --pcflags option to devbox services up

[josh-d2]

Summary

Add new --pcflags option which provides flags directly to process-compose

Motivation

https://github.com/jetify-com/devbox/issues/2105

Usage

The --pcflags flag must be provided in front of each flag as shown below:

devbox services up ${service} \
--pcflags ${flag1} \
--pcflags ${flag2} \
...

How was it tested?

1. Added debugging print statement in manager.go, right before providing the flags to process-compose, to ensure that the flags are being passed down as expected to process-compose.
2. Verified that devbox services up nginx shows the process-compose UI but devbox serviecs up nginx --pcflags -t=false does not show the UI.

[sentry-io[bot]]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ *exec.ExitError: <redacted usererr.combined>: nix path-info exit code: 1, output: <redacted []uint8>, err: <redac...** go.jetpack.io/devbox/internal/nix in StorePaths... View Issue
• ‼️ Generic Error: <redacted errors.withStack>: <redacted usererr.combined> go.jetpack.io/devbox/internal/boxcli/usererr in... View Issue

_{Did you find this useful? React with a 👍 or 👎}