Rework CI workflows (#8688)

- split workflows into separate files to trigger by path
  this should help out documentation and boards / eboot / pkg files
  updates, since those *wont* trigger usual build stuff anymore
- build*.sh whatever merged into just common.sh and build.sh
  trigger different parity builds, mod % rem and allow to set .ino list
  through the environment variable
- removes unnecessary temporary files, try to use more pipes
  move remaining ones into cache dir instead of PWD
- remove legacy TRAVIS env vars, use ESP8266_ARDUINO prefix for config
- remove Windows path workarounds
- hardware/ and ide/ directories are set through envionment
  do not force specific paths, simplify builds on local machine
- sketch list is set through environment. expicit paths for Windows and
  macOS builders. platformio also gets a real shuffled list instead of
  mod and rem magic numbers
- detect root of the repo through git cli, not base{name,dir} or relative paths

tests/ci/pkgrefs_test.sh

@@ -2,8 +2,10 @@
 
 set -ev
 
+root=$(git rev-parse --show-toplevel)
+
 fail=0
-for i in $(cat "$TRAVIS_BUILD_DIR/package/package_esp8266com_index.template.json" | jq '.packages[0]."tools" | .[] | .systems[] | "\(.url) \(.checksum)"' | sort -u | sed 's/ /@/'); do
+for i in $(cat "$root/package/package_esp8266com_index.template.json" | jq '.packages[0]."tools" | .[] | .systems[] | "\(.url) \(.checksum)"' | sort -u | sed 's/ /@/'); do
     url=$(echo $i | sed 's/@/ /' | cut -f2 -d\" | cut -f1 -d' ')
     sha=$(echo $i | sed 's/@/ /' | cut -f2 -d\" | cut -f2 -d' ' | cut -f2 -d:)
     echo "INFO:  Checking $url"