internal/cli: add db.engine flag

[anshalshukla]

Description

With recent changes in geth a new flag was introduced to select upon the database. We already have the required changes after upstream merge, I've just added the flag to select the database.

Changes

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Changes only for a subset of nodes

Breaking changes

N.A

Nodes audience

N.A

Checklist

• I have added at least 2 reviewer or the whole pos-v1 team
• I have added sufficient documentation in code
• I will be resolving comments - if any - by pushing each fix in a separate commit and linking the commit hash in the comment reply
• Created a task in Jira and informed the team for implementation in Erigon client (if applicable)
• Includes RPC methods changes, and the Notion documentation has been updated

Cross repository changes

• This PR requires changes to heimdall
  • In case link the PR here:
• This PR requires changes to matic-cli
  • In case link the PR here:

Testing

• I have added unit tests
• I have added tests to CI
• I have tested this code manually on local environment
• I have tested this code manually on remote devnet using express-cli
• I have tested this code manually on mumbai
• I have created new e2e tests into express-cli

Manual tests

I've tested it locally and it works well.

Additional comments

POS-1763

[codecov]

Codecov Report

Patch coverage: 66.66% and project coverage change: +0.04% 🎉

Comparison is base (d495949) 57.08% compared to head (d342e65) 57.12%.
Report is 6 commits behind head on develop.

❗ Current head d342e65 differs from pull request most recent head 18dd5dc. Consider uploading reports for the commit 18dd5dc to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #964      +/-   ##
===========================================
+ Coverage    57.08%   57.12%   +0.04%     
===========================================
  Files          633      633              
  Lines        77324    77332       +8     
===========================================
+ Hits         44141    44179      +38     
+ Misses       29417    29394      -23     
+ Partials      3766     3759       -7     

Files Changed	Coverage Δ
graphql/graphql.go	32.03% <0.00%> (-0.10%)	⬇️
internal/cli/server/config.go	69.91% <100.00%> (+0.05%)	⬆️
internal/cli/server/flags.go	100.00% <100.00%> (ø)

... and 21 files with indirect coverage changes

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[manav2401]

Few nit picks before merging.

1. Run make docs to update the docs at the end.
2. Update the 9 config.toml files with this value (commented) (in builder and packaging modules).
3. Update example_config.toml in docs/cli.
4. Test it locally to confirm few things like - if pebble db is enabled for fresh node or not, if you start node with leveldb and restart it with pebble are the errors handled correctly or not, etc.

[manav2401]

LGTM, let's wait for the CI to pass.