Support RxDB 12

[cvara]

Minor fixes that enable rxdb-hooks to work with rxdb@12.x. Fixes are backwards compatible with older rxdb versions.

• drop useRxDocument remove useRxDocument's reliance on chained queries
• fix observeNewCollections plugin compatibility issues
• use RxDBQueryBuilderPlugin for testing

Closes #52.

[codecov]

Codecov Report

Merging #54 (c2af67d) into master (b4b0d44) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #54   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            8         8           
  Lines          160       162    +2     
  Branches        37        37           
=========================================
+ Hits           160       162    +2     

Impacted Files	Coverage Δ
src/plugins.ts	100.00% <ø> (ø)
src/useRxDocument.ts	100.00% <100.00%> (ø)

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