Transition `mila code` to RemoteV2 [MT-80]

[lebrice]

Based off of #112

• Support ssh keys with passphrase in mila code (thanks to RemoteV2)
• Adjust code to use RemoteV2.
• Rename code to code_v1, code --> code_v1 for Windows and add a new code implementation for WSL/MacOS/Linux.
  • For now, leaving the current mila code command for Windows users, printing a warning encouraging to switch to WSL.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.67335% with 50 lines in your changes are missing coverage. Please review.

Project coverage is 74.55%. Comparing base (9b4a7cd) to head (1972cf8).

Files	Patch %	Lines
milatools/utils/vscode_utils.py	80.21%	18 Missing :warning:
milatools/cli/code.py	82.43%	13 Missing :warning:
milatools/utils/disk_quota.py	86.95%	9 Missing :warning:
milatools/utils/parallel_progress.py	88.13%	7 Missing :warning:
milatools/cli/commands.py	92.50%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #105 +/- ## ========================================== + Coverage 72.93% 74.55% +1.61% ========================================== Files 15 17 +2 Lines 2176 2283 +107 ========================================== + Hits 1587 1702 +115 + Misses 589 581 -8 ```

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