fix: Resolve absolute path for start action

[colinhacks]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

The start command breaks when nest start is executed with bun (bunx nest start). This is because Node supports running a file w/o an extension (node /path/to/dist/main) but Bun requires an extension.
Issue Number: N/A

What is the new behavior?

Per #2223

This uses require.resolve to resolve the entrypoint to an absolute file path before starting the child process.

Before: /Users/colinmcd94/Documents/repos/nest-cli/nest-app/dist/main
After: /Users/colinmcd94/Documents/repos/nest-cli/nest-app/dist/main.js

This will behave identically to before when using Node, and fixes the command for Bun.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[kamilmysliwiec]

LGTM