The `make install` script, which most users would run via `sudo` to install into `/usr/local`, will use the current umask of the root user when creating certain files and directories. If one uses a restrictive umask by default (e.g. `umask 077`), this means that only the root user will be able to use the full Bitcoin package.

**Expected behavior**

The install script creates all directories and files, including man pages, etc., with permissions `644` / `755`.

**Actual behavior**

Certain folders are created using the default umask, e.g.:

- /usr/local/share/man/man1/
- /usr/local/lib/pkgconfig/
- [...]

This means that only root can access files in these folders and other users won't be able to read the man pages (for example).

**To reproduce**

```bash
$ ./autogen.sh
$ make
$ sudo -iu root
% umask 077
% make install
```

**System information**

OS: Linux
bitcoind version: HEAD
{
    return GetSetting(strArg).isFalse();
}
std::string ArgsManager::GetArg(const std::string& strArg, const std::string& strDefault) const
{
    return GetArg(strArg).value_or(strDefault);
}
std::optional<std::string> ArgsManager::GetArg(const std::string& strArg) const
{
    const util::SettingsValue value = GetSetting(strArg);
    return SettingToString(value);
}
std::optional<std::string> SettingToString(const util::SettingsValue& value)
{
    if (value.isNull()) return std::nullopt;
    if (value.isFalse()) return "0";
    if (value.isTrue()) return "1";
    if (value.isNum()) return value.getValStr();
    return value.get_str();
}
std::string SettingToString(const util::SettingsValue& value, const std::string& strDefault)
{
    return SettingToString(value).value_or(strDefault);
}
int64_t ArgsManager::GetIntArg(const std::string& strArg, int64_t nDefault) const