### What problem does this PR solve?

Refactor code

### Type of change

- [x] Refactoring

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

### What problem does this PR solve?

Fix: When Excel is a formula, the parsed result is a formula, but cannot
be correctly parsed as a value type

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Co-authored-by: tangyu <1@1.com>

### What problem does this PR solve?

Add CSV file parsing support #4552, #5849, #5870

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

Optimize error handling and support parsing of XLS(EXCEL97—2003) files.

### What problem does this PR solve?

if *.xls file is too large, .eg >50M, I get error.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

Add license statement.

### Type of change

- [x] Refactoring

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

…ple sheets

### What problem does this PR solve?
discussed in https://github.com/infiniflow/ragflow/pull/4102
- In excel_parser.py, `total` means the total number of rows in Excel,
but it return in the first iterate, that lead to the wrong `to_page`
- In table.py, it when Excel file has multiple sheets, it will be
divided into multiple parts, every part size is 3000, `data` may be
empty, because it has recorded in the last iterate.
### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

### What problem does this PR solve?

- Update readme
- Add license

### Type of change

- [x] Documentation Update

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

### What problem does this PR solve?

#643 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?


Split Excel into different chunk
### Type of change

- [x] New Feature (non-breaking change which adds functionality)

### What problem does this PR solve?
#651 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

### Type of change

- [x] Refactoring

### What problem does this PR solve?

#384

### Type of change

- [x] Performance Improvement

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

Issue link:#[[Link the issue
here](https://github.com/infiniflow/ragflow/issues/196)]

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Breaking Change (fix or feature that could cause existing
functionality not to work as expected)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Test cases
- [ ] Python SDK impacted, Need to update PyPI
- [ ] Other (please describe):

* clean rust version project

* clean rust version project

* build python version rag-flow