feat: REPLの機能強化

[takejohn]

What

• console.jsをscripts/repl.mjsに移動し、npm run replでREPLを実行できるようにします。
• REPLが実行されている間、グローバル変数が保存されるようにします。
• 入力行を構文解析するとunexpected EOFエラーになる場合、複数行の入力を受け付けるようになります。
• 終了コマンドを.exitに変更します。

Why

Resolve #849

Additional info (optional)

複数行の入力に対応するため、AiScriptSyntaxErrorのサブクラスAiScriptUnexpectedEOFErrorクラスを作成しました。

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 59.64912% with 23 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/parser/syntaxes/common.ts	30.00%	7 Missing ⚠️
src/parser/scanner.ts	37.50%	5 Missing ⚠️
src/parser/syntaxes/expressions.ts	81.25%	3 Missing ⚠️
src/error.ts	60.00%	2 Missing ⚠️
src/parser/syntaxes/statements.ts	33.33%	2 Missing ⚠️
src/parser/syntaxes/toplevel.ts	50.00%	2 Missing ⚠️
src/parser/streams/token-stream.ts	50.00%	1 Missing ⚠️
src/parser/utils.ts	88.88%	1 Missing ⚠️

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Files with missing lines	Coverage Δ
src/parser/streams/token-stream.ts	81.03% <50.00%> (+17.58%)	⬆️
src/parser/utils.ts	97.14% <88.88%> (-2.86%)	⬇️
src/error.ts	89.55% <60.00%> (+3.18%)	⬆️
src/parser/syntaxes/statements.ts	97.35% <33.33%> (+4.09%)	⬆️
src/parser/syntaxes/toplevel.ts	96.15% <50.00%> (-2.41%)	⬇️
src/parser/syntaxes/expressions.ts	93.09% <81.25%> (+3.91%)	⬆️
src/parser/scanner.ts	94.16% <37.50%> (+5.39%)	⬆️
src/parser/syntaxes/common.ts	90.28% <30.00%> (+0.75%)	⬆️

... and 24 files with indirect coverage changes