Merge branch 'en/sparse-checkout-set'

Merge branch 'en/sparse-checkout-set'

The "init" and "set" subcommands in "git sparse-checkout" have been
unified for a better user experience and performance.

* en/sparse-checkout-set:
  sparse-checkout: remove stray trailing space
  clone: avoid using deprecated `sparse-checkout init`
  Documentation: clarify/correct a few sparsity related statements
  git-sparse-checkout.txt: update to document init/set/reapply changes
  sparse-checkout: enable reapply to take --[no-]{cone,sparse-index}
  sparse-checkout: enable `set` to initialize sparse-checkout mode
  sparse-checkout: split out code for tweaking settings config
  sparse-checkout: disallow --no-stdin as an argument to set
  sparse-checkout: add sanity-checks on initial sparsity state
  sparse-checkout: break apart functions for sparse_checkout_(set|add)
  sparse-checkout: pass use_stdin as a parameter instead of as a global