error-stack add serde based serialization

[indietyp]

🌟 What is the purpose of this PR?

Create a serde serialization implementation for Report.

🔗 Related links

• Add serde implementation for error-stack #792: Previous PR, due to internal changes closed in favor of this one

🔍 What does this change?

• non-derive based serde::Serialize implementation, which is gated behind a new feature flag

📜 Does this require a change to the docs?

Yes, while teased in the CHANGELOG.md, the lib.rs documentation and module level documentation need to be adjusted.

🐾 Next steps

• Tests
• (Follow-Up PR): Hooks + Documentation

🛡 What tests cover this?

New snapshot tests that are located in tests/test_ser.rs

📹 Demo

[
  {
    "value": "context A",
    "attachments": [
      "printable C: 4",
    ],
    "sources": [
      {
        "value": "root error",
        "attachments": [
          "printable C: 1",
          "printable C: 3",
        ],
        "sources": [],
      },
      {
        "value": "root error",
        "attachments": [
          "printable C: 2",
          "printable C: 3",
        ],
        "sources": [],
      },
    ],
  },
]

[codecov]

Codecov Report

Merging #1290 (4606aa9) into main (f3025f9) will increase coverage by 0.24%.
The diff coverage is 96.38%.

@@            Coverage Diff             @@
##             main    #1290      +/-   ##
==========================================
+ Coverage   44.58%   44.83%   +0.24%     
==========================================
  Files         315      316       +1     
  Lines       17248    17331      +83     
  Branches      813      813              
==========================================
+ Hits         7690     7770      +80     
- Misses       9553     9556       +3     
  Partials        5        5              

Flag	Coverage Δ
backend-integration-tests	3.20% <ø> (ø)
error-stack	90.76% <96.38%> (+0.31%)	⬆️
unit-tests	1.17% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/libs/error-stack/src/lib.rs	38.46% <ø> (ø)
packages/libs/error-stack/src/serde.rs	96.38% <96.38%> (ø)

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[indietyp]

(Tests fail because the location for some snapshots changed, this will be fixed as soon as I am able to do so)

[TimDiekmann]

@indietyp and I spoke about the exact representation offline and after a few back and forth agreed on a similar representation as we use internally. The contexts will be nested as this is the most intuitive format when a Report is serialized. This has the disadvantage, that long chains of errors will get bigger nesting, but we agreed that serialized reports are mainly used internally, and parsing those should be as straightforward as possible. To pretty print a report, the Debug implementation typically will be used.
The attachments will remain a list inside of each context.

[TimDiekmann]

This looks very good, thank you, I'm super excited about this! Sorry, that it took me so long to review this 🙁

Only have a few comments on the implementation details, the output LGTM 🎉

[TimDiekmann]

Thanks @indietyp for implementing this feature, I'm super excited about that!