feat: add toBuffer method to AE data types

[fredwes]

Co-authored-by: akshayganeshen [email protected]

Implement toBuffer() method for all data types that are supported by Always Encrypted (https://docs.microsoft.com/en-us/sql/relational-databases/security/encryption/always-encrypted-database-engine?view=sql-server-ver15#feature-details). This method will normalize parameter values as buffers to allow them to be encrypted and sent to the database as VarBinary.

This is the first PR of the effort to break down the large Always Encrypted PR into smaller, more manageable ones for review. https://github.com/tediousjs/tedious/pull/1020

[codecov[bot]]

Codecov Report

Merging #1053 into master will decrease coverage by 0.19%. The diff coverage is 99.39%.

@@            Coverage Diff             @@
##           master    #1053      +/-   ##
==========================================
- Coverage   80.77%   80.57%   -0.20%     
==========================================
  Files          86       86              
  Lines        4384     4550     +166     
  Branches      793      837      +44     
==========================================
+ Hits         3541     3666     +125     
- Misses        584      626      +42     
+ Partials      259      258       -1     

Impacted Files	Coverage Δ
src/data-type.ts	100.00% <ø> (ø)
src/data-types/decimal.ts	92.30% <88.88%> (-0.55%)	:arrow_down:
src/data-types/bigint.ts	91.30% <100.00%> (+1.83%)	:arrow_up:
src/data-types/binary.ts	78.37% <100.00%> (+1.90%)	:arrow_up:
src/data-types/bit.ts	100.00% <100.00%> (ø)
src/data-types/char.ts	78.72% <100.00%> (+1.45%)	:arrow_up:
src/data-types/date.ts	63.63% <100.00%> (+13.63%)	:arrow_up:
src/data-types/datetime.ts	100.00% <100.00%> (ø)
src/data-types/datetime2.ts	88.88% <100.00%> (+4.10%)	:arrow_up:
src/data-types/datetimeoffset.ts	88.13% <100.00%> (+4.04%)	:arrow_up:
... and 17 more

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