* [REFACTORING]Rename whitespace_tokenizer to tag_tokenizer for
registration
Name representing its purpose is preferred.
* Add lindera-tantivy to plume-model's dependencies
* Install lindera-tantivy
* Add SearchTokenizerConfig struct
* Add search tokenizers to config option
* Use CONFIG for tokenizers
* Use enum to hold tokenizer config instead of initializing on config phase
* Use guard instead of duplicate default values
* Use as_deref() instead of guard
* Move SearchTokenizer from plume-models to plume-models::search::tokenizer
* Rename SearchTokenizer to TokenizerKind
* Define SearchTokenierConfig::determine_tokenizer()
* Use determine_tokenizer in SearchTokenizerConfig::init()
* Pass tokenizer config to Searcher methods
* Add LowerCase filter to Lindera tokenizer
* Add test for Lindera tokenizer
* Define SEARCH_LANG env to specify tokenizers set
* Run cargo fmt
* Make Lindera tokenizer optional
* Fix typos
92a386277b