Reduce the size of static data in std_unicode::tables.

`BoolTrie` works well for sets of code points spread out through
most of Unicode’s range, but is uses a lot of space for sets
with few, mostly low, code points.

This switches a few of its instances to a similar but simpler trie
data structure.

 ## Before

`size_of::<BoolTrie>()` is 1552, which is added to
`table.r3.len() * 8 + t.r5.len() + t.r6.len() * 8`:

* `Cc_table`: 1632
* `White_Space_table`: 1656
* `Pattern_White_Space_table`: 1640
* Total: 4928 bytes

 ## After

`size_of::<SmallBoolTrie>()` is 32, which is added to
`t.r1.len() + t.r2.len() * 8`:

* `Cc_table`: 51
* `White_Space_table`: 273
* `Pattern_White_Space_table`: 193
* Total: 517 bytes

 ## Difference

Every Rust program with `std` statically linked should be about 4 KB smaller.