Fix incorrect raising of database_does_not_exist error

[nickva]

When we're raising the error with the args list [1], the format for the args is a list of arguments not a single arg. So the previous invocations of erlang:error(database_does_not_exist, ?b2l(Id)) would produce a args list of individual database name characters [2].

[1] https://www.erlang.org/doc/man/erlang#error-2

[2] > mem3_shards:opts_for_db(<<"doesnotexit">>).

** exception error: database_does_not_exist
     in function  mem3_shards:opts_for_db/11
        called as mem3_shards:opts_for_db(100,111,101,115,110,111,116,101,120,105,116)

[nickva]

With the fix it should look like:

(node1@127.0.0.1)1> mem3_shards:opts_for_db(<<"doesnotexist">>).
** exception error: database_does_not_exist
     in function  mem3_shards:opts_for_db/1
        called as mem3_shards:opts_for_db(<<"doesnotexist">>)

[jaydoane]

Of the 4 changes, seems like only the line in fabric_db_create.erl is covered by tests. Still, it's easy to see by inspection that this is the correct fix (as long as DbName is a binary in all cases), so +1 from me.