Update sensing_of fields if variable gets renamed

[apple502j]

Thanks @adroitwhiz and @fsih for some advice! (This is basically re-work of #2330)

Resolves

Resolves scratchfoundation/scratch-gui#4392

Proposed Changes

Adds a new function, updateSensingOfReference, similiar to existing updateAssetName. This checks for every block that

1. has opcode sensing_of
2. has old name in PROPERTY
3. has the same OBJECT
4. doesn't have blocks inserted to OBJECT
   and changes the property.

Reason for Changes

Variable blocks will change their variable name by itself, but sensing_of does not. This will make sensing_of blocks referencing the variable return 0 when they are renamed.

Test Coverage

Added type test and 4 tests:

1. updateSensingOfReference normal behavior
2. updateSensingOfReference block inserted
3. updateSensingOfReference different variable
4. updateSensingOfReference different target

[cwillisf]

These changes look good! In the future, it would help us out if you could just update the existing PR instead of making a new one when changes are requested. Thanks!

[apple502j]

@cwillisf I tried to do that (and TIL force-push won't work well with closed PR!)