[Feature] Handle Japanese text

[PikalaxALT]

Currently the hardcoded charmap is set up to assume all text dumped from the ROM uses the Gen 3 English character set. This means that Japanese text (either untranslated in BPRE or native in BPEJ) is parsed as gibberish. To remedy this, a Japanese mode should be added to the interactive text parsing routine. Suggested specifications:

• In text mode, user should be able to toggle between languages with the command l. This will switch between English and Japanese charsets, and revert at the next putative string.
• When switching languages, the preview shall be parsed anew from the start of the current incbin fragment, allowing the user to view the putative string in both charsets before deciding whether or not it is in fact an agbstring.
• User may toggle a "language lock" using command L to enable or disable reversion to the default language as specified above.
• User may override the default language selection using set followed by language=japanese or language=english (or from the cli call using -c language=japanese). If l is used in text mode, the language will revert to the specified default. If not specified, the default language will be English in order to preserve current behavior.