The tool does not detect whether a release already exists

When this tool assigns a new version to the project, [it takes the current version as specified in `package.json`](https://github.com/MetaMask/create-release-branch/blob/b8bffc55e34103649a65a5d41c4ad6448b473803/src/project.ts#L93) and [increments it](https://github.com/MetaMask/create-release-branch/blob/b8bffc55e34103649a65a5d41c4ad6448b473803/src/workflow-operations.ts#L31). It also uses the same version in the name of the release branch.

This works fine if there are no releases in review when the release branch is created. But what if someone has already created a release and somebody else tries to make a new release? Then the version assigned will be the same as the existing one, and when the user tries to push the branch, they will receive an error.

The tool should look for and consider remote release branches when assigning the new version.

Start with the version handling in src/project.ts and src/workflow-operations.ts, then inspect how the command creates and names release branches. Done means assigning a version that accounts for existing remote release branches so concurrent release attempts do not reuse the same branch version.

Written by the indexing model from the issue text.