Add SameSite to session cookie for PHP 7.2

[MauricioFauth]

• Related to Cookie “phpMyAdmin” will be soon rejected because it has the “sameSite” attribute set to “none” or an invalid value, without the “secure” attribute. #16981

[codecov]

Codecov Report

Merging #17387 (2fd5540) into QA_5_1 (340bff0) will decrease coverage by 0.00%.
The diff coverage is 11.11%.

@@             Coverage Diff              @@
##             QA_5_1   #17387      +/-   ##
============================================
- Coverage     58.06%   58.05%   -0.01%     
- Complexity    15407    15408       +1     
============================================
  Files           472      472              
  Lines         62625    62628       +3     
============================================
- Hits          36362    36361       -1     
- Misses        26263    26267       +4     

Flag	Coverage Δ
arch-7-amd64	61.25% <11.11%> (-0.01%)	⬇️
arch-7-arm32v6	61.14% <11.11%> (-0.01%)	⬇️
arch-7-arm32v7	61.14% <11.11%> (-0.01%)	⬇️
arch-7-arm64v8	61.25% <11.11%> (-0.01%)	⬇️
arch-7-i386	61.14% <11.11%> (-0.01%)	⬇️
arch-7-ppc64le	61.25% <11.11%> (-0.01%)	⬇️
arch-7-s390x	61.11% <11.11%> (-0.01%)	⬇️
dbase-extension	57.60% <11.11%> (-0.01%)	⬇️
recode-extension	57.56% <11.11%> (-0.01%)	⬇️
unit-7.1-ubuntu-latest	57.56% <11.11%> (-0.01%)	⬇️
unit-7.2-ubuntu-latest	57.73% <11.11%> (-0.01%)	⬇️
unit-7.3-ubuntu-latest	61.27% <11.11%> (-0.01%)	⬇️
unit-7.4-ubuntu-latest	61.27% <11.11%> (-0.01%)	⬇️
unit-8.0-ubuntu-latest	61.33% <11.11%> (-0.01%)	⬇️
unit-8.1-ubuntu-latest	61.21% <11.11%> (-0.01%)	⬇️
unit-nightly-ubuntu-latest	61.18% <11.11%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
libraries/classes/Session.php	10.97% <0.00%> (-0.57%)	⬇️
libraries/classes/Config.php	67.82% <33.33%> (-0.06%)	⬇️

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