Detect changed workspaces

[cristiano-belloni]

This PR adds a getChangedWorkspaces to utils, which is a function that takes a branch name and:

1. Gets all the files that git marks as changed between the current state of the repo and the latest commit in common with the specified branch, including untracked and unstaged files. This is handy, for example, to find out the files changed in a PR where the branch specified is the target branch.
2. Gets all the nearest package.json for each of the changed files to compute the containing workspace of each changed file.
3. Matches the list of workspace to the global WorkspaceContent and returns a subset WorkspaceContent containing only the changed workspace info.

Example

const workspaces = await getAllWorkspaces();
const changedWorkspaces = await getChangedWorkspaces(workspaces, "origin/main");

// Assuming that only files in `workspace-1` and `workspace-3` have changed, the result would be:

[
  Map(
    {
      'workspace-1': {
        // Noisy package info, omissis...
      },
      'workspace-3': {
        // Noisy package info, omissis...
      },
    },
   ),
  {
    'workspace-1': {
      location: 'packages/workspace-1',
      workspaceDependencies: ['workspace-2', 'workspace-3'],
      mismatchedWorkspaceDependencies: [],
    },
    'workspace-3': {
      location: 'packages/workspace-3',
      workspaceDependencies: [],
      mismatchedWorkspaceDependencies: [],
    },
  },
]

Tasks:

• Match changed files to the closest package.json, which in turn matches to an entry in workspaceInfo
• Return a subset of the workspaceInfo workspaces, with the same type
• Make it possible to specify a branch in getGitDiff
• Take workspaces in the arguments

[changeset-bot]

🦋 Changeset detected

Latest commit: fcc8957

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
modular-scripts	Minor

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[coveralls]

Coverage increased (+0.3%) to 33.917% when pulling fcc8957 on feature/changed-files-from-merge-base into 12d9ea0 on main.