[Feature] allow customizing the monorepo tag format injected in `context.nextRelease`

[tinesoft]

Hi @pmowrer

First of all, thanks for this awesome project! Exactly what I was looking for to release my Nx-based monorepo (https://github.com/tinesoft/nxrocks).

Is it possible to allow customizing the default monorepo tag format injected in context.nextRelease ? (currently it is <package-name>-v-<version>)

In my case, one of the packages in the monorepo is named: @nxrocks/nx-spring-boot. So the plugin renders @nxrocks/nx-spring-boot-v-<version>, while I would like simply nx-spring-boot/v-<version>...

With the global tagFormat I was able to change the name of the created tag, but this name is not applied everywhere, in particular not in the context.nextRelease.version. Instead, the default format is picked up by the other plugins like @semantic-release/release-notes-generator.

Here is a sample: https://github.com/tinesoft/nxrocks/releases/tag/nx-spring-boot%2Fv2.0.0-beta.1

I believe it is because the default monorepo tag format is hardcoded here: https://github.com/pmowrer/semantic-release-monorepo/blob/413a5702f2381365526fe8928cf56781ea156ddf/src/version-to-git-tag.js#L9

the name is read from the package via const { name } = await readPkg();

An option could be added to allow customizing it.

This is what my .releaserc file looks like:

{
    extends: 'semantic-release-monorepo',
    preset: 'angular',
    plugins: [
      '@semantic-release/commit-analyzer',
      '@semantic-release/release-notes-generator', 
      '@semantic-release/changelog',
      '@semantic-release/github',
      ['@semantic-release/npm', { pkgRoot: relativeBuildOutput }],
      [
        '@semantic-release/exec',
        {
          prepareCmd: [
            formatFile(`${projectRoot}/CHANGELOG.md`),
            copyFile(`${projectRoot}/CHANGELOG.md`, buildOutput),
            copyFile(`${projectRoot}/README.md`, buildOutput),
            copyFile(`LICENSE`, buildOutput),
          ].join(' && '),
          execCwd: relativeWorkspaceRoot,
        },
      ],
      [
        '@semantic-release/git',
        {
          message: releaseCommit,
        },
      ],
    ],
    tagFormat: `${projectScope}/v\${version}` // note: projectScope is dynamically injected
  }