fix: Enforce http2, fix dfx local server not supported by ic-rosetta-api

[TerrorJack]

When dfx starts a local replica, it automatically starts icx-proxy to reroute the incoming requests. It uses hyper for http logic, and hyper doesn't properly support http1/http2 dual stack. The main ic repo assumes http2 in a lot of places, one consequence of that is ic-rosetta-api being unable to connect to the local replica started by dfx. This patch fixes that problem.

See ticket https://dfinity.atlassian.net/browse/ROSETTA1-162 for more context.

[roman-kashitsyn]

@TerrorJack, I believe you need to change the PR title to conform to the guideline (fix: ...). I don't have the permissions to change it myself. Please also add some maintainers as reviewers, e.g., @eric-swanson, I don't have permission to merge this PR.