Switchable tokenizer (#776)

* [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

plume-models/Cargo.toml

@@ -30,6 +30,7 @@ whatlang = "0.7.1"
 shrinkwraprs = "0.2.1"
 diesel-derive-newtype = "0.1.2"
 glob = "0.3.0"
+lindera-tantivy = { version = "0.1.2", optional = true }
 
 [dependencies.chrono]
 features = ["serde"]
@@ -54,3 +55,4 @@ diesel_migrations = "1.3.0"
 [features]
 postgres = ["diesel/postgres", "plume-macro/postgres" ]
 sqlite = ["diesel/sqlite", "plume-macro/sqlite" ]
+search-lindera = ["lindera-tantivy"]