fix: [IOCOM-1994,IOCOM-1995] Fix for back behaviours on FIMS Auth

[Vangaorth]

Short description

This PR fixes some anomalies on the back behaviour for the FIMS' Auth flow

List of changes proposed in this pull request

• When going back from an error screen, proper deallocation of FIMS resources was not triggered (using navigation.back instead of back saga)
• On Android, physical back button event is not handled by the assistance modal and is propagated to the underlying screen. If this happens on the FIMS' consents screen, the flow is interrupted. Since this anomaly affects the entire app, the back capturing has been disabled and the user has to rely on the UI back buttons

How to test

Using the io-dev-api-server, check that:

• the FIMS flow can be successfully retried after an error
• the Android back button does nothing on the FIMS' Auth flow

[pagopa-github-bot]

	Warnings
⚠️	Multiple stories with different types are associated with this Pull request. Only one tag will be added, following the order: feature > bug > chore

Affected stories

• 🐞 IOCOM-1994: [FIMS] Spinner infinito dopo back da FAQ
• 🐞 IOCOM-1995: [FIMS] Errore dopo ripristino connessione dati persa durante spinner dopo consenso

Generated by 🚫 dangerJS against d8da83a

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 48.30%. Comparing base (4f204b4) to head (d8da83a).
Report is 831 commits behind head on master.

Files with missing lines	Patch %	Lines
...s/singleSignOn/components/FimsFullScreenErrors.tsx	0.00%	3 Missing ⚠️
...ims/singleSignOn/screens/FimsFlowHandlerScreen.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6481      +/-   ##
==========================================
- Coverage   48.42%   48.30%   -0.13%     
==========================================
  Files        1488     1578      +90     
  Lines       31617    32265     +648     
  Branches     7669     7389     -280     
==========================================
+ Hits        15311    15585     +274     
- Misses      16238    16625     +387     
+ Partials       68       55      -13     

Files with missing lines	Coverage Δ
...ims/singleSignOn/screens/FimsFlowHandlerScreen.tsx	2.85% <0.00%> (ø)
...s/singleSignOn/components/FimsFullScreenErrors.tsx	5.55% <0.00%> (ø)

... and 1714 files with indirect coverage changes

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[forrest57]

LGTM