Remove files between process runs in watch mode

[jeparlefrancais]

Closes #169

• [x] add entry to the changelog

[github-actions[bot]]

Coverage after merging cleanup-files-in-watch-mode into main will be

86.92%

Coverage Report for Changed Files

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src/cli
process.rs	23.66%	100%	19.05%	24.24%	110–113, 127–130, 132–138, 140–141, 143–148, 151–152, 154–155, 157–159, 163–168, 170–172, 175–181, 184–185, 187–195, 198–199, 201–210, 213–215, 219–225, 227–229, 23, 230, 25, 35, 38, 48–51, 53–57, 59, 82–85, 87–92
src/frontend
process_result.rs	61.11%	100%	53.85%	62.71%	31–33, 43–45, 57–63, 7, 77–83
work_item.rs	80.85%	100%	62.86%	86.79%	121, 161, 5, 57, 80, 98
worker.rs	71.02%	100%	63.16%	71.47%	100–107, 110, 114–115, 118–121, 141–143, 168–169, 171, 194, 199–201, 203, 21, 235, 259–263, 265, 289–292, 297–302, 304–311, 332–334, 342–344, 352–354, 362–364, 366–367, 376, 412, 428–430, 445–447, 49–56, 86–87