Add new property placeholder implementation

This commit provides a rewrite of the parser for properties containing
potentially placeholders.

Assuming a source where `firstName` = `John` and `lastName` = `Smith`,
the "${firstName}-${lastName}" property is evaluated as "John-Smith".

Compared with the existing implementation in PropertyPlaceholderHelper,
the new implementation offers the following extra features:

1. Placeholder can be escaped using a configurable escape character.
When a placeholder is escaped it is rendered as is. This does apply to
any nested placeholder that wouldn't be escaped. For instance,
"\${firstName}" is evaluated as "${firstName}".
2. The default separator can also be escaped the same way. When the
separator is escaped, the left and right parts are not considered as
the key and the default value respectively. Rather the two parts
combined, including the separator (but not the escape separator) are
used for resolution. For instance, ${java\:comp/env/test} is looking
for a "java:comp/env/test" property.
3. Placeholders are resolved lazily. Previously, all nested placeholders
were resolved before considering if a separator was present. This
implementation only attempts the resolution of the default value if the
key does not provide a value.
4. Failure to resolve a placeholder are more rich, with a dedicated
PlaceholderResolutionException that contains the resolution chain.

See gh-9628
See gh-26268

Author: snicoll