增加doc、xlsx文件支持

[leapar]

希望增加word文档、excel文档支持。我写了一个版本，不知道是否合适。

https://github.com/leapar/eino-ext

package indexing

import (
	"context"

	"github.com/cloudwego/eino-ext/components/document/loader/file"
	"github.com/cloudwego/eino-ext/components/document/parser/csv"
	"github.com/cloudwego/eino-ext/components/document/parser/doc"
	"github.com/cloudwego/eino-ext/components/document/parser/pdf"
	"github.com/cloudwego/eino-ext/components/document/parser/xlsx"
	"github.com/cloudwego/eino/components/document"
	"github.com/cloudwego/eino/components/document/parser"
)

// newLoader component initialization function of node 'FileLoader' in graph 'KnowledgeIndexing'
func newLoader(ctx context.Context) (ldr document.Loader, err error) {
	pdfParser, err := pdf.NewPDFParser(&pdf.Config{ToPages: true})
	if err != nil {
		return nil, err
	}

	docParser, err := doc.NewDocParser()
	if err != nil {
		return nil, err
	}

	csvParser, err := csv.NewCsvParser()
	if err != nil {
		return nil, err
	}

	xlsxParser, err := xlsx.NewXlsxParser()
	if err != nil {
		return nil, err
	}
	txtParser := &parser.TextParser{}

	extParser, err := parser.NewExtParser(ctx, &parser.ExtParserConfig{
		FallbackParser: parser.TextParser{},
		Parsers: map[string]parser.Parser{
			".pdf":  pdfParser,
			".txt":  txtParser,
			".md":   txtParser,
			".doc":  docParser,
			".docx": docParser,
			".xlsx": xlsxParser,
			".csv":  csvParser,
		},
	})
	if err != nil {
		return nil, err
	}

	// TODO Modify component configuration here.
	config := &file.FileLoaderConfig{
		Parser: extParser,
	}
	ldr, err = file.NewFileLoader(ctx, config)
	if err != nil {
		return nil, err
	}

	return ldr, nil
}

[meguminnnnnnnnn]

可以直接来提 pr，我们来review