Improve contrast with 'ansi-xx-d' console colourisation.

[timbrown5]

Jenkins and plugins versions report

Environment

```text Paste the output here ```

What Operating System are you using (both controller, and any agents involved in the problem)?

Any OS or browser.

Reproduction steps

1. Install Pipeline Graph View Plugin.
2. Ensure ANSI Plugin global setting is disabled.
3. Write a Pipeline that outputs ANSI codes, e.g.

   pipeline {
   agent none
   options {
       ansiColor('xterm')
   }
   stages {
       stage('Color') {
           steps {
               echo('\033[34mHello\033[0m \033[33mcolorful\033[0m \033[35mworld\033[0m')
           }
       }
   }
   }

4. Run Pipeline
5. View console text in Pipeline Console.

Expected Results

Readable text, e.g.

or:

Actual Results

Text is difficult to read:

Anything else?

We could look at using similar colours to the Dark Theme: https://github.com/jenkinsci/dark-theme-plugin/blob/master/src/main/frontend/main.scss

The classes to override are defined in: https://github.com/jenkinsci/pipeline-graph-view-plugin/blob/main/src/main/frontend/pipeline-console-view/pipeline-console/main/pipeline-console.scss#L92