bundle size is inflated by use of TS/JS classes

[pauldambra]

terser and rollup don't minify class fields and methods so our bundle includes things like this.sessionManager.checkAndGetSessionAndWindowId(!t,e.timestamp) when you might expect it to include o(!t,e.timestamp) after minifying

session recording uses 2 classes: session id manager and session recording and uses long descriptive method names - and is ~ 13% of the final bundle

there is probably an easy win in moving some or all of this to function-based instead of class-based code

[fromaline]

Looks like the code uses a lot of classes

[fromaline]

@pauldambra, do you mean something like this PR?