The "highlight all" and "Pick element" should have configuration for the colors

Problem/Motivation

With the current implementation, the "highlight all" and "Pick element" uses "#2a7ae2" and "#ff9800" respectively.

Steps to reproduce

Click on the "highlight all" button and the notes gets highlighted with "#2a7ae2" colour. And the "Pick element" hilights element in "#ff9800".

Proposed resolution

Have configuration for these colours, so that the highlights does not get invisible for pages that uses these colours for their design.

Remaining tasks

Add a section in the configuration for these two colours to be configured.

User interface changes

Colour updates based on configuration.

API changes

N/A

Data model changes

N/A