[IDP-1764] Add watch mode

[tjosepo]

Description of changes

Add a watch mode. This mode can be accessed using --watch on the CLI or using setting the watch property to true in the config file.

Output:

$ pnpm exec create-schemas --watch                                  
Watching for changes on v1.yaml
✔ Completed in 43ms
    openapi-types.ts (2.2 KB)
Change detected
✔ Completed in 20ms
    openapi-types.ts (2.2 KB)
Configuration changed. Restarting.
Watching for changes on v1.yaml
✔ Completed in 7ms
    openapi-types.ts (2.2 KB)
Configuration changed. Restarting.
Watching for changes on foo.yaml
foo.yaml does not exist.

Breaking changes

None. This change is fully backwards compatible.