Make git add work consistently with subdirectories (#473)

* Make git add work consistently with subdirectories

Currently, depending on your `commitMode`,
when running the action with `cwd` set to a subdirectory of a repo,
the action will either:

- `git-cli`: add the files changed in the subdirectory only
- `github-api`: add files changed anywhere in the repository

This commit brings github-api in line with git-cli,
so that it only adds files in the current working directory.

* Explicitly set `cwd` for all exec calls

* Avoid using `ExecOptions` from `@actions/exec`

* Rename type

* remove redundant `filter`

---------

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

src/index.ts

@@ -15,11 +15,12 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
     return;
   }
 
-  const inputCwd = core.getInput("cwd");
+  const inputCwd = getOptionalInput("cwd");
   if (inputCwd) {
     core.info("changing directory to the one given as the input");
     process.chdir(inputCwd);
   }
+  const cwd = inputCwd || process.cwd();
 
   const octokit = setupOctokit(githubToken);
   const commitMode = getOptionalInput("commitMode") ?? "git-cli";
@@ -27,7 +28,10 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
     core.setFailed(`Invalid commit mode: ${commitMode}`);
     return;
   }
-  const git = new Git(commitMode === "github-api" ? octokit : undefined);
+  const git = new Git({
+    octokit: commitMode === "github-api" ? octokit : undefined,
+    cwd
+  });
 
   let setupGitUser = core.getBooleanInput("setupGitUser");
 
@@ -100,6 +104,7 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
         git,
         octokit,
         createGithubReleases: core.getBooleanInput("createGithubReleases"),
+        cwd,
       });
 
       if (result.published) {