[SystemMonitor] Port detailed memory information to QtWidgets

Currently detailed memory information is displayed as a web page and this implementation has several limitations:

• you can't search the data
• you can't sort data by specific column
• you can't move columns
• it's quite slow and looks outdated

Porting it to QtWidgets removes these limitations and adds some new features:

• general page: shows general information about process
• memory maps page: shows memory consumption for each of the process's mappings
• open files: shows files opened by the process