Highlight code sections

**Is your feature request related to a problem? Please describe.**
There may be multiple places i repeat a piece of code in one query - for example i could write:
`TO_NUMBER(TO_CHAR(SYSDATE-1, 'YYYYMMDD'))`
In multiple places, but if i want to change the date range, i would likely have to change it in all places in occours.

**Describe the solution you'd like**
It would be nice if you could have a piece of code remain consistently highlighted (with a background color of my choice). For example, in this case, i could 'pin' the `TO_NUMBER(TO_CHAR(SYSDATE` portion of the script, so it would appear highlighted everywhere in the SQL file, just so this is easy to find throughout the file.

Something like this:


**Describe alternatives you've considered**
NA

**Additional context**
NA