Consider sharing entrypoint.sh script with other continuous integration solutions

[nicorikken]

There is a potential of reusing the entrypoint.sh for other container-based continuous integration solutions. The entrypoint.sh script could be adopted in the main ORT repository so it is included in all Docker containers and can be referenced by using it as the entrypoint. Or it can just be copied over to each relevant continuous integration solution repository.

[nicorikken]

Currently the default values are set in the github action but not in the entrypoint, resulting in an error when running a container with entrypoint without values:

+ [[ 0 -gt 0 ]]
+ mkdir -p ort/reports
+ mkdir -p ort/results
+ /opt/ort/bin/ort --info analyze -i . -o ort --package-curations-file curations.yml
15:31:42.634 [main] INFO  org.ossreviewtoolkit.model.config.LicenseFilenamePatterns - Configuring the license file patterns.
________ _____________________
\_____  \\______   \__    ___/ the OSS Review Toolkit, version DOCKER-SNAPSHOT.
 /   |   \|       _/ |    |
/    |    \    |   \ |    |    Running 'analyze' under Java 11.0.8 on Linux with
\_______  /____|_  / |____|    8 CPUs and a maximum of 3966 MiB of memory.
        \/       \/
Environment variables:
ORT_CONFIG_DIR = /root/.ort/config
ORT_DATA_DIR = /root/.ort
JAVA_HOME = /opt/java/openjdk
ANDROID_HOME = /opt/android-sdk
GOPATH = /go

Usage: ort analyze [OPTIONS]

Error: Invalid value for "--package-curations-file": File "curations.yml" does not exist.
+ LAST_OUTPUT_FILE=ort/analyzer-result.yml
+ cp ort/analyzer-result.yml ort/results/
cp: cannot stat 'ort/analyzer-result.yml': No such file or directory
+ ''
/entrypoint.sh: line 66: : command not found
+ ''
/entrypoint.sh: line 76: : command not found
+ ''
/entrypoint.sh: line 87: : command not found
+ ''
/entrypoint.sh: line 103: : command not found

[nicorikken]

A separate issue #19 for setting the default values