Use encoded file URI when reading persisted NcML aggregation cache

[387809109]

Description of Changes

The generated cache filename is:

/path/test1.ncml#delimiter

This is a valid Linux filename.
AggregationExisting.persistRead() parsed the cache using:

Parse.readRootElement("file:" + cacheFile.getPath())

For a URL such as file:/path/test1.ncml#delimiter the #delimiter portion is interpreted as a URI fragment.

The XML parser therefore attempted to open /path/test1.ncml instead of /path/test1.ncml#delimiter
The resulting IOException was caught and persistRead() returned silently.

replaced that part with Parse.readRootElement(cacheFile.toURI().toString())
File.toURI() encodes the literal # as %23.

The resulting URI refers to the real file:
test1.ncml%23delimiter

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[387809109]

the cache-sensitive TestNetcdfFileCache.testNetcdfFileCache failure appears unrelated to this one-line URI change.