Add filtering of XCOMs for Dynamic Task Mapping

### Description

Allow filtering mappable XCOMs such that inputs to dynamic task mapping run on a subset of the XCOM.

```python
@task
def get_integers():
return [-1, 0, 1]

@task
def print_x(x):
print(x)

print_x.expand(get_integers().filter(lambda x: x>0))
# Prints:
# 1
```

### Use case/motivation

Currently, this can be implemented with a dedicated task just for filtering. This becomes undesired if you intend to filter to partition the XCOM output as inputs of multiple task (i.e., branching/partitioning):

### Dynamic task branching with XCOM filtering
```python
@task
def get_integers():
return [-1, 0, 1]

@task
def print_x(x):
print(x)

integers = get_integers()
task_print_positive = print_x.expand(integers.filter(lambda x: x>0))
task_print_negatives = print_x.expand(integers.filter(lambda x: x<0))
task_print_zeros = print_x.expand(integers.filter(lambda x: x==0))

# The flow logic is effectively:
# integers >> [task_print_positive, task_print_negatives, task_print_zeros]
```

### Dynamic task branching with Taskflow API
```python
@task
def get_integers():
return [-1, 0, 1]

@task
def print_x(x):
print(x)

@task
def filter_positive(x):
return list(filter(x>0, x))

@task
def filter_negative(x):
return list(filter(x<0, x))

@task
def filter_zero(x):
return list(filter(x==0, x))

integers = get_integers()
task_print_positive = print_x.expand(filter_positive(integers))
task_print_negatives = print_x.expand(filter_negatives(integers))
task_print_zeros = print_x.expand(filter_zeros(integers))

# The flow logic is effectively:
# integers >> [filter_positive >> task_print_positive, filter_negative >> task_print_negatives, filter_zeros >> task_print_zeros]
```

### Related issues

_No response_

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start with the Dynamic Task Mapping and Taskflow API examples in the issue, comparing the proposed filter usage with the current dedicated filtering-task workaround. Define the filtering and branching behavior for mappable XCOMs, then add coverage for positive, negative, and zero partitions; no implementation files or tests are named in the issue.

Written by the indexing model from the issue text.