Allow `_ZO_FZF_OPTS` to not override the useful default values

[clenemt]

_ZO_FZF_OPTS override all the values at the moment. Would it be possible to have another option that keeps the default values? Maybe _ZO_FZF_ADDITIONAL_OPTS or something similar. Happy to push a PR if needed.

[stablestud]

+1

Yes please! I would've liked to remove the FZF borders with --no-border, to align it with the FZF shell completion, but setting the FZF opts removes all Zoxide defaults.

Maybe _ZO_FZF_ADDITIONAL_OPTS or something similar.

Instead of _ZO_FZF_ADDITIONAL_OPTS I would vote for _ZO_FZF_EXTRA_OPTS