Add API endpoint to request contents of multiple files simultaniously (#34139)

Adds an API POST endpoint under `/repos/{owner}/{repo}/file-contents`
which receives a list of paths and returns a list of the contents of
these files.

This API endpoint will be helpful for applications like headless CMS
(reference: https://github.com/sveltia/sveltia-cms/issues/198) which
need to retrieve a large number of files by reducing the amount of
needed API calls.

Close #33495

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/repository/files/file_test.go

@@ -5,13 +5,6 @@ package files
 
 import (
 	"testing"
-	"time"
-
-	"code.gitea.io/gitea/models/unittest"
-	"code.gitea.io/gitea/modules/gitrepo"
-	"code.gitea.io/gitea/modules/setting"
-	api "code.gitea.io/gitea/modules/structs"
-	"code.gitea.io/gitea/services/contexttest"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -31,93 +24,3 @@ func TestCleanUploadFileName(t *testing.T) {
 		assert.Equal(t, expectedCleanName, cleanName)
 	})
 }
-
-func getExpectedFileResponse() *api.FileResponse {
-	treePath := "README.md"
-	sha := "4b4851ad51df6a7d9f25c979345979eaeb5b349f"
-	encoding := "base64"
-	content := "IyByZXBvMQoKRGVzY3JpcHRpb24gZm9yIHJlcG8x"
-	selfURL := setting.AppURL + "api/v1/repos/user2/repo1/contents/" + treePath + "?ref=master"
-	htmlURL := setting.AppURL + "user2/repo1/src/branch/master/" + treePath
-	gitURL := setting.AppURL + "api/v1/repos/user2/repo1/git/blobs/" + sha
-	downloadURL := setting.AppURL + "user2/repo1/raw/branch/master/" + treePath
-	return &api.FileResponse{
-		Content: &api.ContentsResponse{
-			Name:              treePath,
-			Path:              treePath,
-			SHA:               sha,
-			LastCommitSHA:     "65f1bf27bc3bf70f64657658635e66094edbcb4d",
-			LastCommitterDate: time.Date(2017, time.March, 19, 16, 47, 59, 0, time.FixedZone("", -14400)),
-			LastAuthorDate:    time.Date(2017, time.March, 19, 16, 47, 59, 0, time.FixedZone("", -14400)),
-			Type:              "file",
-			Size:              30,
-			Encoding:          &encoding,
-			Content:           &content,
-			URL:               &selfURL,
-			HTMLURL:           &htmlURL,
-			GitURL:            &gitURL,
-			DownloadURL:       &downloadURL,
-			Links: &api.FileLinksResponse{
-				Self:    &selfURL,
-				GitURL:  &gitURL,
-				HTMLURL: &htmlURL,
-			},
-		},
-		Commit: &api.FileCommitResponse{
-			CommitMeta: api.CommitMeta{
-				URL: "https://try.gitea.io/api/v1/repos/user2/repo1/git/commits/65f1bf27bc3bf70f64657658635e66094edbcb4d",
-				SHA: "65f1bf27bc3bf70f64657658635e66094edbcb4d",
-			},
-			HTMLURL: "https://try.gitea.io/user2/repo1/commit/65f1bf27bc3bf70f64657658635e66094edbcb4d",
-			Author: &api.CommitUser{
-				Identity: api.Identity{
-					Name:  "user1",
-					Email: "address1@example.com",
-				},
-				Date: "2017-03-19T20:47:59Z",
-			},
-			Committer: &api.CommitUser{
-				Identity: api.Identity{
-					Name:  "Ethan Koenig",
-					Email: "ethantkoenig@gmail.com",
-				},
-				Date: "2017-03-19T20:47:59Z",
-			},
-			Parents: []*api.CommitMeta{},
-			Message: "Initial commit\n",
-			Tree: &api.CommitMeta{
-				URL: "https://try.gitea.io/api/v1/repos/user2/repo1/git/trees/2a2f1d4670728a2e10049e345bd7a276468beab6",
-				SHA: "2a2f1d4670728a2e10049e345bd7a276468beab6",
-			},
-		},
-		Verification: &api.PayloadCommitVerification{
-			Verified:  false,
-			Reason:    "gpg.error.not_signed_commit",
-			Signature: "",
-			Payload:   "",
-		},
-	}
-}
-
-func TestGetFileResponseFromCommit(t *testing.T) {
-	unittest.PrepareTestEnv(t)
-	ctx, _ := contexttest.MockContext(t, "user2/repo1")
-	ctx.SetPathParam("id", "1")
-	contexttest.LoadRepo(t, ctx, 1)
-	contexttest.LoadRepoCommit(t, ctx)
-	contexttest.LoadUser(t, ctx, 2)
-	contexttest.LoadGitRepo(t, ctx)
-	defer ctx.Repo.GitRepo.Close()
-
-	repo := ctx.Repo.Repository
-	branch := repo.DefaultBranch
-	treePath := "README.md"
-	gitRepo, _ := gitrepo.OpenRepository(ctx, repo)
-	defer gitRepo.Close()
-	commit, _ := gitRepo.GetBranchCommit(branch)
-	expectedFileResponse := getExpectedFileResponse()
-
-	fileResponse, err := GetFileResponseFromCommit(ctx, repo, commit, branch, treePath)
-	assert.NoError(t, err)
-	assert.Equal(t, expectedFileResponse, fileResponse)
-}