Add bcd key insert, retreival, tests

[suprith-hub]

Adds feature search by BCD key.
Addresssing the issue
Majorly:

1. Use and store CompatFeatures from web-platform-dx
2. Create a table to store compat features
3. Query and function to retrieve from table
4. Modify search grammar to support bcd key

[suprith-hub]

@jcscottiii I’ve completed all the changes, and run successful precommit.
It was interesting and my first backend contribution.

During development, I needed to inspect database data, so I used:

kubectl port-forward pod/spanner 9010:9010 9020:9020
spanner-cli -p local -i local -d local --endpoint=localhost:9010

This allowed me to run queries directly against the local Spanner emulator.

We might want to document this workflow for others — including how to debug Go services inside devcontainers — as it makes local development and debugging much smoother.

Let me know what you think!

[suprith-hub]

Also @jcscottiii

Should the search by description be disallowed ?

[suprith-hub]

@jcscottiii can you review this PR.
Can I continue contributing on more issues?