feat(docs): rename x/builder -> x/auction (#55)

* rename x/builder -> x/auction

* update proto / etc.

* integratino fix

---------

Co-authored-by: David Terpay <[email protected]>
(cherry picked from commit 3c6f319)

# Conflicts:
#	block/mempool_test.go
#	lanes/mev/check_tx.go
#	lanes/mev/utils.go
#	lanes/mev/utils_test.go
#	tests/app/app.go
#	tests/app/config.go
#	tests/integration/chain_setup.go
#	tests/integration/pob_integration_test.go
#	testutils/utils.go
#	x/auction/ante/ante.go
#	x/auction/ante/ante_test.go
#	x/auction/client/cli/query.go
#	x/auction/client/cli/tx.go
#	x/auction/keeper/auction.go
#	x/auction/keeper/genesis.go
#	x/auction/keeper/grpc_query.go
#	x/auction/keeper/keeper.go
#	x/auction/keeper/msg_server.go
#	x/auction/module.go
#	x/auction/rewards/fixed_provider.go
#	x/auction/types/msgs_test.go