Refactor CI into multiple workflows and remove Ubuntu 18.04 jobs, as …

…it has been deprecated in GitHub Actions.

.github/scripts/setup_build_ubuntu-20.04.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# Install required packages for CodeCompass build
+sudo apt-get install -y git cmake make g++ libboost-all-dev llvm-10-dev clang-10 \
+  libclang-10-dev odb libodb-dev thrift-compiler libthrift-dev default-jdk libssl-dev \
+  libgraphviz-dev libmagic-dev libgit2-dev ctags doxygen libgtest-dev npm libldap2-dev

.github/scripts/setup_postgresql_ubuntu-20.04.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+# Install PostgreSQL
+sudo apt-get install libodb-pgsql-dev postgresql-server-dev-12

.github/scripts/setup_runtime_ubuntu-20.04.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# Install required packages for CodeCompass runtime
+sudo apt-get install -y git cmake make g++ graphviz \
+  libboost-filesystem1.71.0 libboost-log1.71.0 libboost-program-options1.71.0 \
+  libllvm10 clang-10 libclang1-10 libthrift-0.13.0 default-jre libssl1.1 libmagic1 \
+  libgit2-28 ctags googletest libldap-2.4-2

.github/scripts/setup_sqlite3_ubuntu-20.04.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+# Install SQLite3
+sudo apt-get install libodb-sqlite-dev libsqlite3-dev