Don't require flag to start emulator with `flow dev`

[chasefleming]

Closes #1579

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For contributor use:

• [ ] Targeted PR against master branch
• [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• [ ] Code follows the standards mentioned here
• [ ] Updated relevant documentation
• [ ] Re-reviewed Files changed in the Github PR explorer
• [ ] Added appropriate labels

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 39.31%. Comparing base (0220f8b) to head (1fdb27b).

Files	Patch %	Lines
internal/super/dev.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## feature/interactive-init #1580 +/- ## ========================================================= Coverage 39.31% 39.31% ========================================================= Files 52 52 Lines 3449 3449 ========================================================= Hits 1356 1356 Misses 1926 1926 Partials 167 167 ``` | [Flag](https://app.codecov.io/gh/onflow/flow-cli/pull/1580/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=onflow) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/onflow/flow-cli/pull/1580/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=onflow) | `39.31% <0.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=onflow#carryforward-flags-in-the-pull-request-comment) to find out more.

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