fix: reorganize folder structure of evallib

[osmanyasar05]

This PR reorganizes the folder structure of evallib, the previous structure failed to build due to error:

[stderr]
      error: Multiple top-level modules discovered in a flat-layout: ['main', 'taskqueue'].

Co-authored-by: Sasha Lopoukhine superlopuh@gmail.com

[github-actions]

bv_decide solved 0 theorems.
bitwuzla solved 0 theorems.
bv_decide found 0 counterexamples.
bitwuzla found 0 counterexamples.
bv_decide only failed on 0 problems.
bitwuzla only failed on 0 problems.
both bitwuzla and bv_decide failed on 0 problems.
In total, bitwuzla saw 0 problems.
In total, bv_decide saw 0 problems.
ran rg 'LeanSAT provided a counter' | wc -l, this file found 0, rg found 0, SUCCESS
ran rg 'Bitwuzla provided a counter' | wc -l, this file found 0, rg found 0, SUCCESS
ran rg 'LeanSAT proved' | wc -l, this file found 0, rg found 0, SUCCESS
ran rg 'Bitwuzla proved' | wc -l, this file found 0, rg found 0, SUCCESS
The InstCombine benchmark contains 4520 theorems in total.
Saved dataframe at: /home/runner/work/lean-mlir/lean-mlir/bv-evaluation/raw-data/InstCombine/instcombine_ceg_data.csv
all_files_solved_bitwuzla_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_rw_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_bb_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_sat_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_lratt_times_stddev avg: nan | stddev: nan
all_files_solved_bv_decide_lratc_times_stddev avg: nan | stddev: nan
mean of percentage stddev/av: nan%

[luisacicolini]

Thank you for the PR! Does this cause any changes in the README files for the python scripts? If so, could you update them accordingly?

Otherwise, as for the other PRs, please rebase on main and then merge if CI passes