Add regexManager for Dockerfile and Earthfile

[Kesin11]

Useful config for detecting constant version in Dockerfile and Earthfile that use for download binary from github-releases like this.

# renovate: datasource=github-releases depName=open-telemetry/opentelemetry-collector-releases
ARG OTELCOL_CONTRIB_VERSION=0.70.0 # <= Renovate can detect and replace this version.

RUN curl -LO https://github.com/open-telemetry/opentelemetry-collector-releases/releases/download/v${OTELCOL_CONTRIB_VERSION}/otelcol-contrib_${OTELCOL_CONTRIB_VERSION}_linux_amd64.tar.gz
RUN tar -xvf otelcol-contrib_${OTELCOL_CONTRIB_VERSION}_linux_amd64.tar.gz

reference:

• https://docs.renovatebot.com/modules/manager/regex/#advanced-capture
• https://docs.renovatebot.com/presets-regexManagers/#regexmanagersdockerfileversions
• https://docs.renovatebot.com/user-stories/maintaining-aur-packages-with-renovate/#updating-versions-with-renovate