Add setup for node-reth

[cody-wang-cb]

Adding instruction to https://github.com/base/node-reth under the reth folder, also a README for more info.

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[danyalprout]

Instead of duplicating the existing Reth setup can we parameterize the binary in the existing image? (or use a shared base image).

Parameterizing the binary (with the default being the current version) feels like the way to go IMO. It'll make the images bigger due to having a second binary, but that's a temporary state -- we'll want to make our Reth build the default one.

Approved review 2791311177 from danyalprout is now dismissed due to new commit. Re-request for approval.