fix: enable experimental trace endpoints on polkadot

[TarikGul]

cc:/ @emostov

Enables the tracing endpoints for polkadot.

[emostov]

What is the motivation? Can we just instruct people to add this on their own?

[TarikGul]

Yea I'm fine with closing this and instructing others who want to test this out to add it within the controller config themselves. @Imod7 had brought it up, and tried to run traces with polkadot locally, so my idea was to just add it in as an experimental.

But there is definitely no large precedent.

[Imod7]

I did the change locally (added the BlocksTrace controller for polkadot), run a polkadot node with flag --unsafe-rpc-external but still I cannot see the trace endpoints on sidecar. So I guess there is also another change that I need to do in the node level ?

[TarikGul]

I did the change locally (added the BlocksTrace controller for polkadot), run a polkadot node with flag --unsafe-rpc-external but still I cannot see the trace endpoints on sidecar. So I guess there is also another change that I need to do in the node level ?

I sanity checked this PR before pushing it up and the traces endpoints worked. Did you use yarn build to recompile the code, or are you using yarn dev?

[Imod7]

I run a polkadot node with this command :
./target/release/polkadot --chain=polkadot-dev --tmp --rpc-cors=all --alice --unsafe-rpc-external

Then in sidecar I run
yarn build
substrate-api-sidecar

[TarikGul]

So it should actually be
yarn build
yarn start

[0xslipk]

LGTM