We manually create the parent directories first so that bootstrap failures are detected early on instead of some sub directory during extraction.
Also fixed issue where `TermuxFileUtils.isTermuxFilesDirectoryAccessible()` would not check if a directory file actually existed at TERMUX_FILES_DIR_PATH and may set permissions for a non-directory file at the path. The `TermuxInstaller` was testing if `TERMUX_PREFIX_DIR_PATH` existed later on so check wasn't necessary but function may be called from elsewhere too.
Also removed legacy `PREFIX_FILE*` and `STAGING_PREFIX_FILE*` local constants and use the ones provided by `TermuxConstants` directly.
4e5f2c7e01