fix: validate page tokens for better error codes

[zepatrik]

Currently the error returned is similar to unable to fetch records: ERROR: error in argument for $2: could not parse "1" as type uuid: could not parse "1" as type uuid: uuid: incorrect UUID length: 1 (SQLSTATE 22P02).

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 78.37%. Comparing base (7945104) to head (97cea84).
Report is 9 commits behind head on master.

Files with missing lines	Patch %	Lines
persistence/sql/identity/persister_identity.go	0.00%	1 Missing and 1 partial ⚠️
persistence/sql/persister_session.go	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4021      +/-   ##
==========================================
- Coverage   78.39%   78.37%   -0.02%     
==========================================
  Files         370      370              
  Lines       26127    26133       +6     
==========================================
  Hits        20481    20481              
- Misses       4088     4092       +4     
- Partials     1558     1560       +2     

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