Enable `cache_all` by default

[deivid-rodriguez]

cache_all is a flag to enable caching of gems from git and path sources to vendor/cache. Right now, people using vendor/cache with git and path gems need to explicitly configure this feature flag. Needs agreement on whether this should be kept as a setting (does it make sense for git and path gems to not be included in vendor/cache?), or whether it should be the default and only behavior.

[flavorjones]

Just a note that cache_all will also cache all platforms that are present in the lock file (without it, only the local platform's gems are cached).

One data point: I am in favor of making this behavior the default.

[deivid-rodriguez]

@flavorjones I think that's (confusingly) the cache_all_platforms setting which I believe it's unrelated to cache_all?

[flavorjones]

@deivid-rodriguez Ah, I guess you're right.