v1.16: add merkle root meta column to blockstore (backport of #33979)

[mergify]

This is an automatic backport of pull request #33979 done by Mergify.
Cherry-pick of e457c02 has failed:

On branch mergify/bp/v1.16/pr-33979
Your branch is up to date with 'origin/v1.16'.

You are currently cherry-picking commit e457c02879.
  (fix conflicts and run "git cherry-pick --continue")
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Changes to be committed:
	modified:   ledger/src/blockstore/blockstore_purge.rs
	modified:   ledger/src/blockstore_db.rs
	modified:   ledger/src/blockstore_meta.rs

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   ledger/src/blockstore.rs

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[codecov]

Codecov Report

Merging #34046 (aaa877e) into v1.16 (1776575) will decrease coverage by 0.1%.
The diff coverage is 53.8%.

Additional details and impacted files

@@            Coverage Diff            @@
##            v1.16   #34046     +/-   ##
=========================================
- Coverage    81.8%    81.8%   -0.1%     
=========================================
  Files         766      766             
  Lines      209076   209102     +26     
=========================================
- Hits       171168   171130     -38     
- Misses      37908    37972     +64     

[AshwinSekar]

This commit also includes #34091

[behzadnouri]

lgtm, but please wait for Steve to confirm we are good to backport this to v1.16.

[AshwinSekar]

backport is no longer necessary with the addition of #34174