Matching PR #883 in the message-format-wg repo.
Also move spec tests for unsupported statements and expressions into new files
to serve as syntax error tests.
ICU4C: Escape curly braces when serializing and normalizing
ICU4C: Escape '|' in patterns
ICU4C: When normalizing input, escape optionally-escaped characters in patterns
ICU4C/ICU4J: Allow trailing whitespace after a match
ICU4C: Fix parser to iterate over code points, not code units
Add tests with old reserved syntax as syntax-error tests
This also updates the spec tests from the current version of the MFWG
repository and removes some duplicate tests.
Spec tests now reflect the message-format-wg repo as of
5612f3b050
It also updates both the ICU4C and ICU4J parsers to follow the
current test schema in the conformance repository.
This includes adding code to both parsers to allow `src` to be
either a single string or an array of strings (per
https://github.com/unicode-org/conformance/pull/255 ),
and eliminating `srcs` in tests.
It also includes other changes to make updated spec tests pass:
ICU4C: Allow trailing whitespace for complex messages, due to spec change
ICU4C: Parse number literals correctly in Number::format
ICU4J: Allow trailing whitespace after complex body, per spec change
ICU4C: Fix bug that was assuming an .input variable can't have a reserved annotation
ICU4C: Fix bug where unsupported '.i' was parsed as an '.input'
ICU4C/ICU4J: Handle markup with space after the initial left curly brace
ICU4C: Check for duplicate variant errors
ICU4C/ICU4J: Handle leading whitespace in complex messages
ICU4J: Treat whitespace after .input keyword as optional
ICU4J: Don't format unannotated number literals as numbers
Modify ICU4C and ICU4J test readers to handle all tests
Add `ignoreJava` and `ignoreCpp` properties to tests where needed
Includes parser bug fixes:
ICU4J: require a complex-body after declarations
ICU4J: Correctly parse the complex body after an unsupported statement
ICU4J: Handle date params in tests and remove default params for tests
ICU4J: Handle decimal params in tests
ICU4J: Require whitespace before variable/literal in reserved annotation
ICU4J: Require whitespace between options
ICU4J: Require a variable-expression in an .input declaration
ICU4J: don't require space between last key and pattern in variant
ICU4J: don't require space between selectors
ICU4J: allow whitespace after '=' in option
ICU4J: parse escape sequences in quoted literals according to grammar
ICU4J: allow whitespace within markup after attributes list
