File name filtering does not work when the escapeString is the same as the file separator

### Affected version

3.3.1

### Bug description

On Windows, configure the maven-resources-plugin with `fileNameFiltering=true` and `escapeString=\`. Attempt to copy a resource from a subfolder of a resource directory, where the filename begins with a maven property. For example, use the following pom.xml:

4.0.0

com.test
FileNameFiltering
0.0.1-SNAPSHOT

FileNameFiltering
Reproduction of file name filtering bug

myFileName

maven-resources-plugin
3.3.1





maven-resources-plugin


copy-resources-filter-filename
process-resources

copy-resources


${project.build.outputDirectory}
true
\


${project.basedir}/src/main/custom-resources
false

and create empty file `src\main\custom-resources\folder\${file.name}.txt`. Expected result is the file `target\classes\folder\myFileName.txt` is created. Instead, `target\classes\folder${file.name}.txt` is created, where the subdirectory is lost and becomes part of the file name, which is not filtered.

It appears the filtering is applied to the relative path name as a whole, `folder\${file.name}.txt`, and the file separator is treated as an escape. The filtering should be applied to each file component separately, to remove the conflict with the file separator.

Presumably this can also be reproduced on linux/mac by setting `escapeString=/`, tho this is more likely to be an issue on Windows, since using `escapeString=\` is a common practice.

See the reproduction in this [GitHub repo](https://github.com/pbarnes-tibco/maven-resources-plugin-issue)

Start with the reproduction repository and its pom.xml, then run the Windows case using fileNameFiltering=true and escapeString=\. Inspect how the relative path folder\${file.name}.txt is filtered; done means the output is target\classes\folder\myFileName.txt without losing the subdirectory.

Written by the indexing model from the issue text.