Support migration from AWS CodeCommit (#31981)

This PR adds support for migrating repos from [AWS
CodeCommit](https://docs.aws.amazon.com/codecommit/latest/userguide/welcome.html).

The access key ID and secret access key are required to get repository
information and pull requests. And [HTTPS Git
credentials](https://docs.aws.amazon.com/codecommit/latest/userguide/setting-up-gc.html)
are required to clone the repository.

<img
src="https://github.com/user-attachments/assets/82ecb2d0-8d43-42b0-b5af-f5347a13b9d0"
width="680" />

The AWS CodeCommit icon is from [AWS Architecture
Icons](https://aws.amazon.com/architecture/icons/).

<img
src="https://github.com/user-attachments/assets/3c44d21f-d753-40f5-9eae-5d3589e0d50d"
width="320" />

go.mod

@@ -23,6 +23,9 @@ require (
 	github.com/PuerkitoBio/goquery v1.9.2
 	github.com/SaveTheRbtz/zstd-seekable-format-go/pkg v0.7.2
 	github.com/alecthomas/chroma/v2 v2.14.0
+	github.com/aws/aws-sdk-go v1.43.21
+	github.com/aws/aws-sdk-go-v2/credentials v1.17.30
+	github.com/aws/aws-sdk-go-v2/service/codecommit v1.25.1
 	github.com/blakesmith/ar v0.0.0-20190502131153-809d4375e1fb
 	github.com/blevesearch/bleve/v2 v2.4.2
 	github.com/buildkite/terminal-to-html/v3 v3.12.1
@@ -146,6 +149,10 @@ require (
 	github.com/andybalholm/cascadia v1.3.2 // indirect
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be // indirect
 	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.30.4 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.16 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.16 // indirect
+	github.com/aws/smithy-go v1.20.4 // indirect
 	github.com/aymerick/douceur v0.2.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bits-and-blooms/bitset v1.13.0 // indirect