fix(core): 在排序中不将空字符串视为 undefined

[1wkk]

👀 PR includes

🐛 Bugfix

• Solve the issue and close 🐛交叉表自定义排序会将空字符串置底 #2244

🔧 Chore

• Test case

📝 Description

not consider empty string as undefined, include empty string item in the sort action

🖼️ Screenshot

Before	After
❌	✅

🔍 Self-Check before the merge

• Add or update relevant docs.
• Add or update relevant demos.
• Add or update test case.
• Add or update relevant TypeScript definitions.

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Name	Status	Preview	Comments	Updated (UTC)
antvis-s2	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 28, 2023 9:03am

[codecov]

Codecov Report

Patch coverage: 73.07% and project coverage change: -0.10% ⚠️

Comparison is base (1adc25d) 76.48% compared to head (7f8673e) 76.38%.
Report is 55 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2249      +/-   ##
==========================================
- Coverage   76.48%   76.38%   -0.10%     
==========================================
  Files         240      240              
  Lines       12312    12447     +135     
  Branches     2630     2673      +43     
==========================================
+ Hits         9417     9508      +91     
+ Misses       1377     1371       -6     
- Partials     1518     1568      +50     

Files Changed	Coverage Δ
packages/s2-core/src/cell/col-cell.ts	89.18% <ø> (-0.02%)	⬇️
packages/s2-core/src/cell/corner-cell.ts	83.33% <0.00%> (+0.64%)	⬆️
packages/s2-core/src/cell/row-cell.ts	73.57% <ø> (+0.23%)	⬆️
packages/s2-core/src/cell/table-col-cell.ts	86.53% <ø> (+4.72%)	⬆️
...ackages/s2-core/src/common/constant/interaction.ts	100.00% <ø> (ø)
packages/s2-core/src/data-set/base-data-set.ts	93.93% <ø> (+0.39%)	⬆️
packages/s2-core/src/data-set/pivot-data-set.ts	72.39% <0.00%> (-0.73%)	⬇️
packages/s2-core/src/sheet-type/pivot-sheet.ts	86.30% <0.00%> (+0.19%)	⬆️
packages/s2-core/src/theme/index.ts	92.30% <ø> (-7.70%)	⬇️
packages/s2-core/src/utils/cell/data-cell.ts	77.08% <ø> (ø)
... and 33 more

... and 3 files with indirect coverage changes

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