feat: Modularization: Terraform changes for schema overrides

[manitgupta]

This should only be merged once #1840 is merged.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 53.26%. Comparing base (add3dd7) to head (3aee74f). Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1841      +/-   ##
============================================
+ Coverage     45.56%   53.26%   +7.69%     
+ Complexity     3721     1408    -2313     
============================================
  Files           847      382     -465     
  Lines         50169    20836   -29333     
  Branches       5273     2101    -3172     
============================================
- Hits          22862    11099   -11763     
+ Misses        25632     9054   -16578     
+ Partials       1675      683     -992     

Components	Coverage Δ
spanner-templates	68.35% <ø> (+1.34%)	:arrow_up:
spanner-import-export	∅ <ø> (∅)
spanner-live-forward-migration	75.91% <ø> (ø)
spanner-live-reverse-replication	76.87% <ø> (ø)
spanner-bulk-migration	86.56% <ø> (ø)

see 482 files with indirect coverage changes

[manitgupta]

#1840 is merged, will wait for the release to happen to merge this since it introduces new parameters.