Describe your change:

• Add an algorithm?
  – Added a professional Suffix Array construction (build_suffix_array) using the doubling method and LCP Array construction (build_lcp_array) via Kasai’s algorithm in strings/suffix_array.py.

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file.
• All new Python files are placed inside an existing directory (strings/).
• All filenames are in all lowercase characters with no spaces or dashes (suffix_array.py).
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.

```python

build_suffix_array("banana")
[5, 3, 1, 0, 4, 2]
build_lcp_array("banana", build_suffix_array("banana"))
[1, 3, 0, 0, 2]
```

• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
  – References in docstrings:
  https://cp-algorithms.com/string/suffix-array.html
  https://en.wikipedia.org/wiki/LCP_array
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: “Fixes #ISSUE-NUMBER”.

If you filed a corresponding issue (e.g. “Add suffix array”), add at the bottom of “Describe your change”:
Fixes #1234