Handling of deprecated / hidden commands hydrate & prepare

[MikeMcC399]

Issue

• The following commands are hidden since PR Refactoring of the CLI interface #291 implemented RFC: New command names (and alias the old ones) #274:

corepack hydrate

corepack prepare

These commands:

1. are not documented in the README
2. have no migration guide to their replacement commands
3. do not appear in the output of corepack --help
4. are described in the output of corepack hydrate --help and corepack prepare --help
5. neither their usage, nor their help text indicates that the commands are deprecated

Several issues lately have shown users reporting problems when executing corepack prepare.

corepack prepare is listed as a valid command in Node.js documentation Corepack latest v18. (Node.js v20, v22 & v23 describe instead corepack use / corepack install.)

Suggestion

1. Describe the above commands as deprecated and either add the migration table from RFC: New command names (and alias the old ones) #274 to the README or create a separate Migration Guide document.
2. Extend the help text for the commands to indicate that they are deprecated.
3. Output a deprecation warning if deprecated commands are used.

Also review Node.js documentation Corepack latest v18 and initiate an update if possible.