blockservice: remove inner fields access methods

[Jorropo]

I'll do changelog once we decide on an option.

[Jorropo]

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• #564 👈 (View in Graphite)
• #563
• #560 : 3 other dependent PRs (#556 , #561 , #565 )
• #559
• #558
• main

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[codecov[bot]]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (a76d47d) 65.45% compared to head (783f4ca) 65.40%.

@@                                          Coverage Diff                                          @@
##           01-15-blockservice_move_session_handling_as_part_of_the_interface     #564      +/-   ##
=====================================================================================================
- Coverage                                                              65.45%   65.40%   -0.06%     
=====================================================================================================
  Files                                                                    207      207              
  Lines                                                                  25606    25602       -4     
=====================================================================================================
- Hits                                                                   16760    16744      -16     
- Misses                                                                  7367     7375       +8     
- Partials                                                                1479     1483       +4     

Files	Coverage Δ
gateway/blocks_backend.go	42.27% <0.00%> (-0.10%)	:arrow_down:
blockservice/blockservice.go	75.72% <37.50%> (-1.34%)	:arrow_down:

... and 14 files with indirect coverage changes