Upgrade to be compatible with pyfirecreset v2.6.0

[khsrali]

• Some TODO's are done
• Wherever relevant issues opened and addressed in aiida-core, pyfirecrest, and firecrest
• Added new tests. The old tests, although more sophisticated is harder to debug. New tests focuses only on aiida-firecrest by mocking pyfirecrest only, not firecrest server.
• Current states still depends on un-merged PR#6043, but functional with latest features of aiida v2.5.2

[khsrali]

Thanks a lot @agoscinski for your review, I'll wait for more comments :)

[unkcpz]

As discussed with @khsrali offline, I am fine with removing integration test by using firecrest image to mock some real response. As @khsrali pointed out, pyfirecrest did not do it as well. But I'd suggest to still keep it in mind and open an issue to remember to bring it back with the help from CSCS people to provide a robust and easy to deploy docker-compose solution.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 79.17808% with 76 lines in your changes missing coverage. Please review.

Project coverage is 79.94%. Comparing base (eb7f751) to head (7254af5).

Files	Patch %	Lines
aiida_firecrest/transport.py	82.25%	55 Missing :warning:
aiida_firecrest/scheduler.py	61.81%	21 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #36 +/- ## ========================================== + Coverage 76.25% 79.94% +3.68% ========================================== Files 6 4 -2 Lines 1057 678 -379 ========================================== - Hits 806 542 -264 + Misses 251 136 -115 ``` | [Flag](https://app.codecov.io/gh/aiidateam/aiida-firecrest/pull/36/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | Coverage Δ | | |---|---|---| | [pytests](https://app.codecov.io/gh/aiidateam/aiida-firecrest/pull/36/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.94% <79.17%> (+3.68%)` | :arrow_up: | 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=aiidateam#carryforward-flags-in-the-pull-request-comment) to find out more.

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