This patch fixes a bug where a sublibrary overwrites a library
directory.  This leads to overwriting `*.haddock` files, which results
in missing entries in various indexes (e.g. the html index,
quicksearch).

This patch makes `haddock-project` use `--local` option by default.
Since its the default, it is removed. Also `--gen-index`,
`--gen-contents`, `--hyperlinked-source` and `--quickjump` are removed
since they are always turned on.

Added a haddock-project test.

`haddock-project` command need to build the project so that haddocks of
the dependencies are available in the store.

Fixes #8958.