Assembler: clone-all from link-index registry

[reakaleek]

Context

With these changes the assembler build is more resilient, as it only fetches successfully built commits.

Changes

• Change the RepositorySourcesFetcher to be able to fetch a specific commit.
• clone-all command not fetches the commits from the link-index registry.

How to test

Try the following commands

dotnet run --project src/tooling/docs-assembler -- repo clone-all --environment prod --fetch-latest
dotnet run --project src/tooling/docs-assembler -- repo clone-all --environment prod
dotnet run --project src/tooling/docs-assembler -- repo clone-all --environment staging --fetch-latest
dotnet run --project src/tooling/docs-assembler -- repo clone-all --environment staging

[Copilot]

Pull Request Overview

This PR reworks the repository cloning logic to fetch specific commits from the link-index registry and updates the CLI command accordingly.

• Renamed and refactored the repository fetching method to support commit-specific cloning.
• Updated the CLI command to use the new cloning logic and added configuration documentation for fetchLatest behavior.
• Changed the repository configuration by updating the CheckoutStrategy property to an enum.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/tooling/docs-assembler/Sourcing/RepositorySourcesFetcher.cs	Refactored method renamed to CloneAll with commit-specific fetching via the link-index registry.
src/tooling/docs-assembler/Cli/RepositoryCommands.cs	Updated clone-all CLI command to handle the new fetchLatest parameter and call the updated cloning method.
src/Elastic.Documentation.Configuration/Assembler/Repository.cs	Converted CheckoutStrategy from string to enum for improved type safety.

Comments suppressed due to low confidence (1)

src/tooling/docs-assembler/Sourcing/RepositorySourcesFetcher.cs:75

• The variable 'context' used later (e.g., context.Collector.EmitError(...)) is not defined. Replace it with the appropriate diagnostics collector instance or variable that is in scope.

if (!linkRegistry.Repositories.TryGetValue(repo.Key, out var entry))

[Mpdreamz]

LGTM! just a few q?'s.

[Mpdreamz]

Whats our use-case for this? I like the flag but just wondering :)

[reakaleek]

For local QAing, if you specify a different branch for a repo e.g. feature/new-content, you want to be able to fetch the latest.

[reakaleek]

In general I wanted to keep the old behaviour. Just in case.

[Mpdreamz]

Why is this necessary? (not questioning it just looking to learn).

[reakaleek]

It's actually unlikely.. But I was just thinking, if you ever change the checkout strategy and if you run the command, while the repo is still checked out (cached) you want to also disabled it.

[Mpdreamz]

Suprised how little effect --cone mode actually has on the size on the disk. Runs contrary to: https://github.blog/open-source/git/bring-your-monorepo-down-to-size-with-sparse-checkout/#sparse-checkout-and-partial-clones

[reakaleek]

I think because cone mode is the default according to https://git-scm.com/docs/git-sparse-checkout#_internalscone_mode_handling