Add transformer definition

[olblak]

Fix #160
Fix #152

Add the parameter transformers for every stage definitions, "source", "condition", and "target".
A "transformers" contains a list of transformer rule which are applied successively to the source value.
Each transformer applies a different rule

We also deprecated string manipulation like prefix/postfix/replacer defined outside a transformers definition

transformer

• addPrefix, add a prefix to the source value
• addSuffix, add a suffix to the source value
• trimPrefix, remove the source value prefix
• trimSuffix, remove the source value suffix
• replacer, replace a substring by another one in the source value
• find, return the first occurrence that matches the regex

source:
  name: "Get latest jenkins weekly version"
  kind: jenkins
  transformers:
    - addPrefix: "alpha-"
    - addSuffix: "-jdk11"
    - trimSuffix: "-jdk11"
    - suffix: "-jdk11"
    - replacer:
        from: "-jdk11"
        to: "-jdk15"
    - replacers:
        - from: "-jdk15"
          to: "-jdk17"
  spec:
    release: weekly
targets:
  targetID:
    name: "Update file file"
    kind: file
    spec:
      file: TODO

This rule should generate the value "alpha-2.277-jdk11"

Signed-off-by: Olivier Vernin olivier@vernin.me

[olblak]

Add "add" to prefix and suffix