feat: allow 'git commit' and 'git push' during the prepare and/or publish step

[jfairley]

Updates the plugin to allow for commit and push to execute during "prepare" or "publish" or both. By default, commit and push executes during the "prepare" step.

Examples

The default configuration executes commit/push during "prepare":

module.exports = {
	plugins: [
		['@semantic-release/git', {
			assets: ['pom.xml'],
			message: 'my message'
		}]
	]
};

A user may choose to explicitly call out the "prepare" step:

module.exports = {
	plugins: [
		['@semantic-release/git', {
			prepare: {
				assets: ['pom.xml'],
				message: 'my message'
			}
		}]
	]
};

A user may choose to execute commit/push during the "publish" step:

module.exports = {
	plugins: [
		['@semantic-release/git', {
			publish: {
				assets: ['pom.xml'],
				message: 'my message'
			}
		}]
	]
};

A user may choose to execute commit/push during the "prepare" and "publish" steps:

module.exports = {
	plugins: [
		['@semantic-release/git', {
			prepare: {
				assets: ['pom.xml'],
				message: 'my prepare message'
			},
			publish: {
				assets: ['pom.xml'],
				message: 'my publish message'
			}
		}]
	]
};

Finally, the old-school plugin definitions are also supported:

module.exports = {
	prepare: [{
		path: '@semantic-release/git',
		assets: ['pom.xml'],
		message: 'my prepare message'
	}],
	publish: [{
		path: '@semantic-release/git',
		assets: ['pom.xml'],
		message: 'my publish message'
	}]
};

closes #121
closes #123

[jfairley]

I'm having test parallelism issues, because there's multiple "commit" integration tests. Still working on it.

[pvdlg]

You opened 2 PRs but in none of them, as far as I can tell, you made the case for implementing a new feature. We won't consider any feature or new option without without a strong case supporting its merit.

I'm not really sure what workflow you are trying to support, but at minimum you have to explain what problem you are trying to solve, why it's the best way to solve this problem and how it can benefit semantic-release users in general.

For information, it's quite unlikely that we would modify our core plugins to support a very specific workflow used by a handful of users. Such cases should be covered with custom plugins.
Keep in mind that an additional option might not seems much but in reality it means more code/tests for us to maintain on the long run, more information to digest for users and ultimately more support tickets for us to handle.

If the feature you are trying to implement would bring value for the overall community and you can make the case for it we will definitely consider it.

[jfairley]

@pvdlg I appreciate your feedback. I'll open a simple "issue" to lay out my problem statement. Family needs pending (😉), I'll work on that later tonight.

[jfairley]

@pvdlg Sorry. Some things came up. I'm still going to make a write-up.

[pvdlg]

Closing per #123 (comment)