Most fixes are about code style.

Major changes are in:
1. the algorithm to determine if type is apparent in creation or conversion methods.
2. option serialization/deserialization.

I'd overlooked the fact that !isChecked enforces `use explicit type` and
hadn't stored enforcement level values then. This fixes the bug.

... with notification levels and also test notification levels.

If notification option is set to none, do not show a diagnostic.

.. and push common code down into Abstract base class. CheckBox
ViewModel and CheckBoxWithCombo ViewModel then derive from the abstract
base class.

Rename several internal types appropriately. Update file names to match
them. etc.

Adding Enforcement Levels to each `use var` option. Enforcement levels are: None, Info, Warning and Error.

To do:
unit tests need to be unbroken
refactoring to base classes and to be more generic
fix xaml styling and remove any hardcoded values.
fix up todo comments in code

These are additive minor changes to code naming, styling, documentation,
tests and such. No major functional changes.

We now detect a conversion, if any, do not suggest use var if it changes semantics, as it would for some implicit conversions.
We also recognize type conversion patterns for IsTypeApparent(). For e.g., we recognize static helpers like `int.Parse`, `Convert.ToString()` and instance method `IConvertible.ToChar` etc.

localize all the string resources for use var or use explicit typing
analyzers and fixers.

Changed the UI from combinations of radio buttons and check boxes to use
just checkboxes. Also changed how the partitions of `use var` space was
logically represented. We now present 3 options - use var on intrinsic
types, use var where apparent, use var in rest of the places. If all 3
are checked, we universally use var everywhere. If only one or a
combination less than 3 are selected, we use var only in those places.
An unchecked option means, user prefers explicit typing for that
scenario.

Not yet implemented : enforcement levels of the fix, fancy previews that
show results for a combination of choices, integrating the options into
code generation service.

Remove relay command implementation and usages in checkbox view model.
trying another UI approach to make this simpler.

Add RelayCommand to CheckBoxViewModel to enable/disable checkboxes in
option preview control depending on the state of other controls. The
StyleViewModel now makes use of this for Use Var feature.

Refactor UseImplicitTyping and UseExplicitTyping Analyzers to use an
abstract base class and share common functionalities. Also wire up
options into unit tests.

add options to codestyle for use implicit or explicit typing
analyzer/fixers.

Add an analyzer and fixer for using explicit type over var for C#. Plus,
unit tests.

Add logic to determine if return type information is obvious from the
initializer expression of variable declaration. Currently it recognizes
3 patterns - literals, object creation expressions and static helpers
like `int.Parse`

shelving, edit this commit later.

Initial implementation of a diagnostic analyzer and codefixer for `use
var` style in C#

Merge master into future

Disallow local byref void methods.

Fixes #8441

Ref returns and Locals

The feature needs to be properly implemented taking into account that variable is byref.
For now disabling this refactoring if variable happen to be byref to avoid crash as described in #8416

Ideally EE should not encounter ByRef types, but for now I just make EE resilient if it sees them

member declaration parse should not be considered not advanced when "ref" keyword was consumed.

Fixes #8402