fix(table_service): support both underlying types for YSON bytes and text

[ulya-sidorina]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

TableService scanner handles YSON inconsistently: it expects YSON as TextValue, while other parts of SDK accept YSON as either TextValue or BytesValue.
As a result, scanning via TableService fails when server returns YSON as BytesValue.

Issue Number: NYDB-2083

What is the new behavior?

TableService scanner supports both underlying types for YSON: TextValue and BytesValue.

Other information

[codecov-commenter]

Codecov Report

❌ Patch coverage is 53.57143% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.03%. Comparing base (d9d2943) to head (90ac8b6).

Files with missing lines	Patch %	Lines
internal/table/scanner/scanner.go	53.57%	13 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (d9d2943) and HEAD (90ac8b6). Click for more details.

HEAD has 36 uploads less than BASE

Flag	BASE (d9d2943)	HEAD (90ac8b6)
macOS	4	2
unit	10	6
go-1.26.x	8	3
windows	4	2
ubuntu	8	2
go-1.21.x	8	3
integration	6	0
ydb-edge	2	0
ydb-latest	2	0
ydb-24.4	2	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #2077       +/-   ##
===========================================
- Coverage   72.55%   46.03%   -26.52%     
===========================================
  Files         427      426        -1     
  Lines       36904    36794      -110     
===========================================
- Hits        26774    16937     -9837     
- Misses       8944    19230    +10286     
+ Partials     1186      627      -559     

Flag	Coverage Δ
go-1.21.x	45.98% <53.57%> (-26.54%)	⬇️
go-1.26.x	46.02% <53.57%> (-26.46%)	⬇️
integration	?
macOS	46.02% <53.57%> (+<0.01%)	⬆️
ubuntu	46.01% <53.57%> (-26.53%)	⬇️
unit	46.03% <53.57%> (+<0.01%)	⬆️
windows	46.01% <53.57%> (-0.01%)	⬇️
ydb-24.4	?
ydb-edge	?
ydb-latest	?

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.