Extend LeastSquaresMovingAverage to accept a benchmark reference

[0xpinara]

Description

Adds a Least Squares Moving Average that fits the target prices against a
reference symbol instead of against time. There is a new
LSMA(target, reference, period) overload.

I didn't change the old LeastSquaresMovingAverage. It is a WindowIndicator,
and that puts every input into one window, so it can't hold two symbols. The new
class uses DualSymbolIndicator, like Beta and Correlation do. That base class
matches the two symbols by time.

The comment on the issue shows a slightly different signature. It is from May
2024, and DualSymbolIndicator was only added in January 2025. So I followed the
newer pattern. I can change it if you prefer.

Related Issue

Resolves #6984. It replaces my earlier attempt in #9371. #9426 also targets this
issue, so tell me if you'd rather use that one.

Motivation and Context

LSMA could only fit prices against time. There was no built in way to fit them
against a benchmark like SPY.

Requires Documentation Change

Yes, the new overload.

How Has This Been Tested?

The tests use CommonIndicatorTests, like the other dual symbol indicators. I
added an LSMAWithReference column to bi_datatest.csv. I worked those numbers
out with the least squares formula myself, so they don't come from the indicator.
There is also a test that does the same fit by hand without MathNet, and two tests
in AlgorithmIndicatorsTests.

All of QuantConnect.Tests.Indicators passes. 2988 passed, 0 failed, 5 skipped.

Took me a while to work out why SPY and BTCUSD never paired up. The indicator just
sat at 0 and there was no error. MultiSymbolIndicator rounds the timestamps down
before it compares them, added in #8564, and that rounding only runs when the input
has a duration. IndicatorDataPoint has none, so it got skipped. Bars have one, so
the problem goes away. The test is WorksWithDifferentTimeZones.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>