Several updates have been made to full-text search Named schemas

## Feature Feature Several updates have been made to [full-text search](https://cloud.google.com/spanner/docs/full-text-search): * [Named schemas](https://cloud.google.com/spanner/docs/full-text-search/search-indexes#create%5Fand%5Fquery%5Fa%5Fsearch%5Findex%5Ffor%5Fa%5Fnamed%5Fschema)now support full-text search. * Spanner search indexes can now[accelerate pattern matching expressions](https://cloud.google.com/spanner/docs/full-text-search/pattern-matching-function-acceleration)such as `LIKE`, `STARTS_WITH`, and `ENDS_WITH` for pattern matching, and`REGEXP_CONTAINS` for regular expression matching. * [TOKENIZE\_FULLTEXT](https://cloud.google.com/spanner/docs/reference/standard-sql/search%5Ffunctions#tokenize%5Ffulltext)now has an argument for removing diacritics. `SEARCH` and `SCORE` automatically use this if the data was tokenized with this option. * [TOKENIZE\_SUBSTRING](https://cloud.google.com/spanner/docs/full-text-search/substring-search) now supports emojis.