feat: Read file separator from server config

[mofojed]

• Uses the file separator specified in the server config
• Fixes Treat files as opaque strings to support different file systems #2046
• Add context FileStorageContext for getting the FileStorage

BREAKING CHANGE: Implementations of FileStorage must now provide the readonly separator: string property

[codecov]

Codecov Report

Attention: Patch coverage is 48.34437% with 78 lines in your changes missing coverage. Please review.

Project coverage is 46.48%. Comparing base (e75e716) to head (e69d64a).
Report is 9 commits behind head on main.

Files	Patch %	Lines
packages/file-explorer/src/NewItemModal.tsx	0.00%	23 Missing ⚠️
...ashboard-core-plugins/src/panels/NotebookPanel.tsx	0.00%	20 Missing ⚠️
packages/file-explorer/src/FileExplorer.tsx	61.11%	6 Missing and 1 partial ⚠️
packages/code-studio/src/main/AppInit.tsx	0.00%	6 Missing ⚠️
...kages/dashboard-core-plugins/src/ConsolePlugin.tsx	16.66%	5 Missing ⚠️
...ages/app-utils/src/storage/grpc/GrpcFileStorage.ts	0.00%	4 Missing ⚠️
...es/app-utils/src/storage/grpc/GrpcLayoutStorage.ts	0.00%	4 Missing ⚠️
packages/file-explorer/src/FileList.tsx	25.00%	3 Missing ⚠️
...app-utils/src/storage/grpc/GrpcFileStorageTable.ts	66.66%	2 Missing ⚠️
packages/file-explorer/src/useFileStorage.ts	0.00%	2 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2118      +/-   ##
==========================================
- Coverage   46.64%   46.48%   -0.17%     
==========================================
  Files         679      685       +6     
  Lines       38632    38487     -145     
  Branches     9792     9590     -202     
==========================================
- Hits        18020    17890     -130     
- Misses      20560    20586      +26     
+ Partials       52       11      -41     

Flag	Coverage Δ
unit	46.48% <48.34%> (-0.17%)	⬇️

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