context list: temporarily add ContextType to JSON output

[thaJeztah]

• [x] depends on / stacked on https://github.com/docker/cli/pull/5097

Docker Desktop currently ships with the "cloud integration" wrapper, which outputs an additional ContextType field in the JSON output.

While this field is non-standard, it made its way into Visual Studio's Docker integration, which uses this to exclude "aci" and "eci" context types that are not supported by Visual Studio.

This patch;

• conditionally adds a ContextType field to the JSON output
• but ONLY when using the default "{{json .}}" or "json" formats (which are the formats used by Visual Studio)
• if the context is a "aci" or "eci" context, that type is preserved, otherwise the default "moby" type is used.

- Description for the changelog

Add a temporary `ContextType` field to the JSON output of "docker context ls" for backward-compatibility with Visual Studio.

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 72.72727% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 61.37%. Comparing base (3da25f6) to head (fed9fa0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5094 +/- ## ======================================= Coverage 61.37% 61.37% ======================================= Files 298 298 Lines 20707 20718 +11 ======================================= + Hits 12708 12716 +8 - Misses 7099 7102 +3 Partials 900 900 ```

[thaJeztah]

Interesting; for some reason static check does NOT complain about using deprecated field 🤔 wondering if we have some config incorrect in golangci-lint; I would expect it to barf;

8.45 cli/command/context/list.go:70:52: directive `//nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.` is unused for linter "staticcheck" (nolintlint)
68.45               ContextType: getContextType(nil, opts.format), //nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.
68.45                                                              ^
68.45 cli/command/context/list.go:87:69: directive `//nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.` is unused for linter "staticcheck" (nolintlint)
68.45           ContextType: getContextType(meta.AdditionalFields, opts.format), //nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.
68.45                                                                            ^
68.45 cli/command/context/list.go:105:51: directive `//nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.` is unused for linter "staticcheck" (nolintlint)
68.45           ContextType: getContextType(nil, opts.format), //nolint:staticcheck // ignore SA1019: field is deprecated, but used for backward-compatibility.

[krissetto]

The binary with this patch will only be used with DD for the upcoming release (and maybe one after that?), is that correct?

[thaJeztah]

Yes(ish); I wanted to avoid having to build some forked version of the CLI, so tried to create a patch with as minimal-as-possible impact, so that we could included it in a v26.1.4 patch release.

[krissetto]

so that we could included it in a v26.1.4 patch release.

if this does go out to "everyone" (and not only dd users), we need to document this in a visible way and be ready in case anything else breaks (i guess, just in case any other project depends on the shape of that json in even worse ways?)

[thaJeztah]

I added 3 commits to improve test-coverage; last commit is the change related to ContextType PTAL

[thaJeztah]

Maybe it's cleaner to move those 3 commits to a separate PR, so that this PR is only showing the changes related to ContextType; let me open a separate PR for the first 3 commits

[thaJeztah]

I'll rebase this one to get rid of the other commits

[thaJeztah]

Rebased and moved out of draft