Support collection of expression-bodied (lambda) methods in C#

[aalramadan]

Stereocode currently does not support the collection of methods defined using expression-bodied (lambda) syntax. Similar to the issue with read-only properties, these methods are often parsed by srcML as expression statements <expr_stmt> rather than <function> elements. For example:

public string GetMessage() => "Hello from lambda method";

srcML

<expr_stmt><expr><specifier>public</specifier> <name>string</name> <name>GetMessage</name><lambda><parameter_list>()</parameter_list> =&gt;<block type="pseudo"><block_content> <expr><literal type="string">"Hello from lambda method"</literal></expr></block_content></block></lambda></expr>;</expr_stmt></unit>

Stereocode should identify expression-bodied members and parse them as methods.