[FEATURE] add percentile information for job ad compensation

[ghost]

it would be nice to understand how a certain job ad compensation stands compared to other jobs for the same location. For example if a job in germany pays 80-100/year. This info would be presented as "This salary range is higher than 90% of jobs for the same location" (90th percentile). Percentile information is readily available already https://golang.cafe/Golang-Developer-Salary-Germany and we could expand the brackets to include more bands (not only 10,50,90 percentile) but more (10,20,30,40,50,60,70,80,90,95,99). Minimal UI change is required in job advert page and on each job preview in the home page.