[BUG] - io.opencaesar.oml.util.OmlCatalog.CatalogEx#makeAbsolute needs to use path calculations

[NicolasRouquette]

Description

A clear and concise description of what the bug is.

This function is invoked when the XML parser is reading a rewrite uri catalog entry.

io.opencaesar.oml.util.OmlCatalog.CatalogEx#makeAbsolute can be invoked as follows:

• baseUri = file:/C:/some/directory/oml
• sysid = file:/

This will produce an invalid result like this: file:/C:/some/directory/oml/file:/

The correct result should be: file:/C:/some/directory/oml/

Steps to Reproduce

Steps to reproduce the behavior:

• Step 1 This bug is reproducible with oml 1.0.3 on windows where a catalog like this:

<?xml version='1.0'?>
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer="public">
	<rewriteURI
		rewritePrefix="file:./"
		uriStartString="http://"/>
</catalog>

Expected Behavior

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Additional Context

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Relevant screenshots

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[NicolasRouquette]

The catalog should have instead:

<?xml version='1.0'?>
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer="public">
	<rewriteURI
		rewritePrefix="./"
		uriStartString="http://"/>
</catalog>