Fix cli test that blocks building on Windows

[BtcContributor]

This fix a path issue that was blocking users to build Bisq on Windows from terminal when using a command like gradlew.bat build

Fix tested on Windows and Linux/macOS.

The error was:

Task :cli:test FAILED

bisq.cli.opt.OptionParsersTest > testCreatePaymentAcctOptParserWithInvalidPaymentFormOptValueShouldThrowException() FAILED
    org.opentest4j.AssertionFailedError at OptionParsersTest.java:179

Due to:

testCreatePaymentAcctOptParserWithInvalidPaymentFormOptValueShouldThrowException()

org.opentest4j.AssertionFailedError: expected: <json payment account form '/tmp/milkyway/solarsystem/mars' could not be found> but was: <json payment account form '\tmp\milkyway\solarsystem\mars' could not be found>
	at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
	at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:177)
	at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1124)
	at bisq.cli.opt.OptionParsersTest.testCreatePaymentAcctOptParserWithInvalidPaymentFormOptValueShouldThrowException(OptionParsersTest.java:179)

[ghubstan]

ACK

[ripcurlx]

utACK based on #5436 (review)